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[多选题]共用题干 Black Holes1 Black holes can be best described as a sort of vacuum,sucking up everything in space.Scientists have discovered that black holes come from an explosion of huge stars.Stars that are near death can no longer burn due to loss of fuel , and because its temperature can no longer control the gravitational(重力的)force,hydrogen ends up putting pressure onto the star's surface until it suddenly explodes then collapses.2 Black holes come from stars ihat are made of hydrogen,other gases and a few metals.When these explode it can turn into a stellar-mass(恒星质量) black hole , which can only occur if the star is large enough (should be bigger than the sun)for the explosion to break it into pieces,and the gravity starts to compact every piece into the tiniest particle.Try to see and compare:if a star that's ten times the size of the sun ends up being a black hole that's no longer than 70 kilometers,then the Earth would become a black hole that'S only a fraction of an inch!3 Objects that get sucked in a black hole will always remain there,never to break free.i1it remember that black holes can only gobble up(吞噬)objects within a specific distance to it.It's possible for a large star near the sun to become a black hole,but the sun will continue to stay in place.Orbits(轨道)do not change because the newly formed black hole contains exactly the same amount of mass as when it was a star, only this time its mass is totally contracted that it can end up as no bigger than a state.4 Sofar,astronomers have figured out that black holes exist because of Albert Einstcin's theory of relativity.In the end,through numerous studies,they have discovered that black holes truly exist.Since black holes trap light and do not give off light,it is nearly impossible to detect black holes via a telescope.But astronomers continue to study galaxies(银河系), space and the solar system to understand how black holes might evolve.It is possible that black holes can exist for millions of years,and later contribute to a bigger process in galaxies,which can eventually lead to creation of new entities(实体).Scientists also credit black holes as helpful in learning how galaxies began to form. Paragraph 3 _________
[多选题]共用题干 Black Holes1 Black holes can be best described as a sort of vacuum,sucking up everything in space.Scientists have discovered that black holes come from an explosion of huge stars.Stars that are near death can no longer burn due to loss of fuel , and because its temperature can no longer control the gravitational(重力的)force,hydrogen ends up putting pressure onto the star's surface until it suddenly explodes then collapses.2 Black holes come from stars ihat are made of hydrogen,other gases and a few metals.When these explode it can turn into a stellar-mass(恒星质量) black hole , which can only occur if the star is large enough (should be bigger than the sun)for the explosion to break it into pieces,and the gravity starts to compact every piece into the tiniest particle.Try to see and compare:if a star that's ten times the size of the sun ends up being a black hole that's no longer than 70 kilometers,then the Earth would become a black hole that'S only a fraction of an inch!3 Objects that get sucked in a black hole will always remain there,never to break free.i1it remember that black holes can only gobble up(吞噬)objects within a specific distance to it.It's possible for a large star near the sun to become a black hole,but the sun will continue to stay in place.Orbits(轨道)do not change because the newly formed black hole contains exactly the same amount of mass as when it was a star, only this time its mass is totally contracted that it can end up as no bigger than a state.4 Sofar,astronomers have figured out that black holes exist because of Albert Einstcin's theory of relativity.In the end,through numerous studies,they have discovered that black holes truly exist.Since black holes trap light and do not give off light,it is nearly impossible to detect black holes via a telescope.But astronomers continue to study galaxies(银河系), space and the solar system to understand how black holes might evolve.It is possible that black holes can exist for millions of years,and later contribute to a bigger process in galaxies,which can eventually lead to creation of new entities(实体).Scientists also credit black holes as helpful in learning how galaxies began to form. When a large star explodes,the gravity compacts every piece into______.
[多选题]共用题干 第二篇Students Learn Better with Touchscreen DesksObserve the criticisms of nearly any major public education system in the world,and a few of the many complaints are more or less universal.Technology moves faster than the education system.Teachers must teach at the pace of the slowest student rather than the fastest. And一particularly in the United States一 school children as a group don't care much for,or excel(擅长)at,mathemnatics. So it's heartening to learn that a new kind of"classroom of the future"shows promise at easing some of these problems,starting with that fundamental piece of classroom furniture:the desk.A UK study involving roughly 400 students,mostly aged 8一10 years,and a new generation of multis-touch,multi-user,computerized desktop surfaces is showing that over the last three years the technology has appreciably boosted students'math skills compared with peers learning the same material via the con- ventional paper-and-pencil method.How?Through collaboration,mostly,as well as by giving teachers better tools by which to micromanage individual students who need some extra instruction while allowing the rest of the class to continue moving forward.Traditional instruction still shows respectable efficacy(效力)at increasing students'fluency in mathe- matics,essentially through memorization and practice一dull,repetitive practice.But the researchers have con-cluded that these new touchscreen desks boost both fluency and flexibility一the critical thinking skills that al- low students to solve complex problems not simply through knowing formulas and devices,but by being able to figure out what the real problem is and the most effective means of stripping it down and solving it.One reason for this,the researchers say,is the multi-touch aspect of the technology.Students working in the next-gen classroom can work together at the same tabletop,each of them contributing and engaging with the problem as part of a group.Known as SynergyNet,the software uses computer vision systems that see in the infrared(红外线的)spectrum to distinguish between different touches on different parts of the surface, allowing students to access and use tools on the screen,move objects and visual aids around on their desk- tops,and otherwise physically interact with the numbers and information on their screens.By using these screens collaboratively,the researchers say,the students are to some extent teaching themselves as those with a stronger grasp on difficult concepts pull other students forward along with them. How does the new tech work to improve students'mathematical learning?
[多选题]共用题干 Climate Change:The Long Reach1.Earth is warming.Sea levels are rising.There's more carbon in the air,and Arctic ice is melting faster than at any time in recorded history.Scientists who study the environment to better gauge(评估) Earth's future climate now argue that these changes may not reverse for a very long time.2.People burn fossil fuels like coal and oil for energy.That burning releases carbon dioxide,a colorless gas.In the air,this gas traps heat at Earth's surface.And the more carbon dioxide released,the more the planet warms.If current consumption of fossil fuels doesn't slow,the long-term climate impacts could last thousands of years-and be more severe than scientists had been expecting.Climatologist RichardZeebe of the University of Hawaii at Manoa offers this conclusion in a new paper.3.Most climate-change studies look at what's going to happen in the next century or so.During that time, changes in the planet' s environment could nudge(推动)global warming even higher.For example, snow and ice reflect sunlight back into space.But as these melt,sunlight can now reach-and warm-the exposed ground.This extra heat raises the air temperature even more,causing even more snow to melt.This type of rapid exaggeration of impacts is called a"fast feedback".4.Zeebe says it's important to look at fast feedbacks.However,he adds,they're limited.From a climate change perspective,"This century is the most important time for the next few generations,"he told Science News."But the world is not ending in 2100."For this new study,Zeebe now focuses on"slow feedbacks".While fast feedback events unfold over decades or centuries,slow feedbacks can take thousands of years.Melting of continental ice sheets and the migration of plant life-as they relocate to more comfortable areas-are two examples of slow feedbacks.5.Zeebe gathered information from previously published studies investigating how such processes played out over thousands of years during past dramatic changes in climate.Then he came up with a forecast for the future that accounts for both slow and fast feedback processes.Climate forecasts that use only fast feedbacks predict a 4.5 degree Celsius(8.1 degree Fahrenheit)change by the year 3000.But slow feedbacks added another 1.5℃-for a 6℃ total increase,Zeebe reports.He also found that slow feedback events will cause global warming to persist for thousands of years after people run out of fossil fuels to burn. Melting of snow and ice enables sunlight to reach______.
[单选题]Can you hear This?   When something creates a sound wave in a room or an auditorium, listeners hear the sound wave directly from the source. They also hear the reflections as the sound bounces off the walls, floor, and ceiling. These are called the reflected wave or reverberant(反射的)sound, which can be heard even after the sound is no longer coming from the source.   The reverberation time of an auditorium is determined by the volume or interior size of the auditorium. It is also determined by how well or how poorly the walls, ceiling, floor, and contents of the room (including the people) absorb sound. There is no ideal reverberation time. Because each use of an auditorium calls for different reverberation. Speech needs to be understood clearly: therefore rooms used for talking must have a short reverberation time. The full-sound performance of music such as Wagner operas or Mahler symphonies should have a long reverberation time. The light, rapid musical passages of Bach or Mozart need a reverberation time somewhere between.   Acoustic problems often are caused by poor auditorium design. Smooth, curved reflecting surfaces create large reflections. Parallel(平行的)walls reflect sound back and forth, creating a rapid, repetitive pulsing effect. Large pillars(柱)and corners can cause acoustic shadows as the sound waves try to pass around the object. Some of these problems can be solved by using absorbers and reflectors to change the reverberation time of a room. For example, hanging large reflectors, called clouds, over the performers will allow some sound frequencies to reflect and others to pass to achieve a pleasing mixture of sound. 文章(41~45) This passage is mainly about_____
[多选题]共用题干 Black Holes1 Black holes can be best described as a sort of vacuum,sucking up everything in space.Scientists have discovered that black holes come from an explosion of huge stars.Stars that are near death can no longer burn due to loss of fuel , and because its temperature can no longer control the gravitational(重力的)force,hydrogen ends up putting pressure onto the star's surface until it suddenly explodes then collapses.2 Black holes come from stars ihat are made of hydrogen,other gases and a few metals.When these explode it can turn into a stellar-mass(恒星质量) black hole , which can only occur if the star is large enough (should be bigger than the sun)for the explosion to break it into pieces,and the gravity starts to compact every piece into the tiniest particle.Try to see and compare:if a star that's ten times the size of the sun ends up being a black hole that's no longer than 70 kilometers,then the Earth would become a black hole that'S only a fraction of an inch!3 Objects that get sucked in a black hole will always remain there,never to break free.i1it remember that black holes can only gobble up(吞噬)objects within a specific distance to it.It's possible for a large star near the sun to become a black hole,but the sun will continue to stay in place.Orbits(轨道)do not change because the newly formed black hole contains exactly the same amount of mass as when it was a star, only this time its mass is totally contracted that it can end up as no bigger than a state.4 Sofar,astronomers have figured out that black holes exist because of Albert Einstcin's theory of relativity.In the end,through numerous studies,they have discovered that black holes truly exist.Since black holes trap light and do not give off light,it is nearly impossible to detect black holes via a telescope.But astronomers continue to study galaxies(银河系), space and the solar system to understand how black holes might evolve.It is possible that black holes can exist for millions of years,and later contribute to a bigger process in galaxies,which can eventually lead to creation of new entities(实体).Scientists also credit black holes as helpful in learning how galaxies began to form. Paragraph 4__________
[多选题]共用题干 Musical Training Can Improve Communication SkillsAmerican scientists say musical training seems to improve communication skills and language retardation (延迟).They found that developing musical skill involves the______(51)process in the brain as learning how to speak.The scientists believe that could______(52)children with learning disabilities.Nina Krauss is a neurobiologist at Northwestern University in Illinois.She says musical training______(53)putting together different kinds of information,such as hearing music,looking at musical notes,touching an instrument and watching other musicians.This______(54)is not much different from learning how to speak.Both involve different senses.She further explains musical training and learning to______(55)each make us think about what we are doing.She says speech and music______(56)through a structure of the nervous system called the brain stem.The brain stem______(57)our ability to hear.Until recently,experts have thought the brain stem could not be developed or changed.______(58)Professor Krauss and her team found that musical training can improve a person's brain stem activity.The study involved individuals with different levels of musical______(59).They were asked to wear an electrical device that measures______(60)activity.The individuals wore the electrode while they watched a video of someone speaking and a person playing a musical instrument-the cello(大提琴).Professor Krauss says cellos have sound qualities similar______(61)some of the sounds that are impor-tant with speech.The study found that the more years of training people had,the more______(62)they were to the sound and rhythm of the music.Those who were involved in musical activities were the same people in whom the______(63)of sensory events was the strongest.It shows the importance of musical training to children with learning______(64).She says using music to improve listening skills could mean they______(65)sentences and understand facial expressions better. _________65
[多选题]共用题干 第三篇Eye-tracker Lets You Drag and Drop Files with a GlanceBored of using a mouse?Soon you'11 be able to change stuff on your computer screen-and then move it directly onto your smartphone or tablet(平板电脑)-with nothing more than a glance.A system called EyeDrop uses a head-mounted eye tracker that simultaneously records your field of view so it knows where you are looking on the screen.Gazing at an object-a photo,say-and then pressing a key,selects that object.It can then be moved from the screen to a tablet or smartphone just by glancing at the second device,as long as the two are connected wirelessly."The beauty of using gaze to support this is that our eyes naturally focus on content that we want toacquire,"says Jayson Turner,who developed the system with colleagues at Lancaster University,UK.Turner believes EyeDrop would be useful to transfer an interactive map or contact information from a public display to your smartphone or tablet for sharing photos.A button needs to be used to select the object you are looking at otherwise you end up with the"Midas touch"(点石成金)effect, whereby everything you look at gets selected by your gaze, says Turner."Imagine if your mouse clicked on everything it pointed at,"he says.Christian Holz,a researcher in human-computer interaction at Yahoo Labs in Sunnyvale,California, says the system is a nice take on getting round this fundamental problem of using gaze-tracking to interact."EyeDrop solves this in a slick(灵巧的)way by combining it with input on the touch devices we carry with us most of the time anyway and using touch input as a clutching mechanism,"he says."This now allows users to seamlessly(无缝地)interact across devices far and close in a very natural manner."While current eye-trackers are rather bulky,mainstream consumer devices are not too far away.Swedish firm Tobii is developing gaze-tracking technology that can be installed in laptops and tablets and is expected to be available to buy next year.And the Google Glass headset is expected to include eye-tracking in the future.Turner says he has also looked at how content can be cut and pasted or drag-and-dropped using a mix of gaze and taps on a touchscreen.The system was presented at the Conference on Mobile and Ubiquitous Multimedia in Sweden,last week. The word"this"in Paragraph 6 refers to______.
[多选题]共用题干 Underground Coal FiresCoal burning deep underground in China,India and Indonesia is threatening the environment and human life , scientists have warned.These large-scale______(51)blazes(火焰)cause the ground temperature to heat up and kill surrounding vegetation,produce greenhouse gases and can______(52) ignite(点燃)forest fires , a group of scientists told the annual meeting of the American Association for theAdvancement of Science in Denver.The resulting______(53)of poisonous elements like mercury can also pollute local water sources and soils,they warned."Coal fires are a global disaster,"said Associate Professor Glenn Stracher of East Georgia College inSwainsboro,USA.But______(54)few people know about them.Coal can heat up on its own,and eventually catch fire and bum,if there is a continuous oxygen supply.The heat produced is not caused to______(55)and under the right combinations of sunlight and oxygen,can trigger spontaneous(自发的)catching fire and buming.This can occur underground , in coal stockpiles, abandoned mines or even as coal is transported.______(56)fires in China consume up to 200 million tons of coal per year,delegates were told.In______(57),the U.S.economy consumes about one billion tons of coal annually,said Stracher,______(58)analysis of the likely impact of coal fires has been accepted for publication in the International Journal of Coal Ecology.______(59)underway,coal fires can bum for decades,even centuries.In the process,they release large______(60)of greenhouse gases,poisonous fumes and black particles into the atmosphere.The members of the panel discussed the______(61)these fires may be having on global and regional climate change,and agreed that the underground nature of the fires makes them difficult to______(62).Ultimately,the remote sensing and other techniques should allow scientists to______(63)how much carbon dioxide these fires are emitting(释放).One suggested______(64)of containing the fires was presented by Gary Colaizzi,of the engineering firm Goodson,which has developed a heat-resistant grout(灌浆),which is designed to be pumped into the coal fire to______(65)the oxygen supply. _________51
[多选题]共用题干 第二篇Eye-tracker Lets You Drag and Drop Files With a GlanceBored of using a mouse?Soon you'11 be able to change stuff on your computer screen-and then move it directly onto your smartphone or tablet(平板电脑)-with nothing more than a glance.A system called EyeDrop uses a head-mounted eye tracker that simultaneously records your field of view, so it knows where you are looking on the screen.Gazing at an object-a photo,say-and then pressing a key, selects that object.It can then be moved from the screen to a tablet or smartphone just by glancing at the second device,as long as the two are connected wirelessly."The beauty of using gaze to support this is that our eyes naturally focus on content that we want to acquire,"says Jayson Turner,who developed the system with colleagues at Lancaster University,UK.Turner believes EyeDrop would be useful to transfer an interactive map or contact information from a public display to your smartphone or tablet for sharing photos.A button needs to be used to select the object you are looking at otherwise you end up with the"Midas touch"(点石成金)effect , whereby everything you look at gets selected by your gaze , says Turner."Imagine if your mouse clicked on everything it pointed at,"he says.Christian Holz,a researcher in human-computer interaction at Yahoo Labs in Sunnyvale,California, says the system is a nice take on getting round this fundamental problem of using gaze-tracking to interact." EyeDrop solves this in a slick(灵巧的)way by combining it with input on the touch devices we carry with us most of the time anyway and using touch input as a clutching mechanism,"he says."This now allows users to seamlessly(无缝地)interact across devices far and close in a very natural manner."While current eye-trackers are rather bulky,mainstream consumer devices are not too far away.Swedish firm Tobii is developing gaze-tracking technology that can be installed in laptops and tablets and is expected to be available to buy next year.And the Google Glass headset is expected to include eye-tracking in the future.Turner says he has also looked at how content can be cut and pasted or drag-and-dropped using a mix of gaze and taps on a touchscreen.The system was presented at the Conference on Mobile and Ubiquitous Multimedia in Sweden,last week. What is Turner likely to study next?
[多选题]共用题干 Musical Training Can Improve Communication SkillsAmerican scientists say musical training seems to improve communication skills and language retardation (延迟).They found that developing musical skill involves the______(51)process in the brain as learning how to speak.The scientists believe that could______(52)children with learning disabilities.Nina Krauss is a neurobiologist at Northwestern University in Illinois.She says musical training______(53)putting together different kinds of information,such as hearing music,looking at musical notes,touching an instrument and watching other musicians.This______(54)is not much different from learning how to speak.Both involve different senses.She further explains musical training and learning to______(55)each make us think about what we are doing.She says speech and music______(56)through a structure of the nervous system called the brain stem.The brain stem______(57)our ability to hear.Until recently,experts have thought the brain stem could not be developed or changed.______(58)Professor Krauss and her team found that musical training can improve a person's brain stem activity.The study involved individuals with different levels of musical______(59).They were asked to wear an electrical device that measures______(60)activity.The individuals wore the electrode while they watched a video of someone speaking and a person playing a musical instrument-the cello(大提琴).Professor Krauss says cellos have sound qualities similar______(61)some of the sounds that are impor-tant with speech.The study found that the more years of training people had,the more______(62)they were to the sound and rhythm of the music.Those who were involved in musical activities were the same people in whom the______(63)of sensory events was the strongest.It shows the importance of musical training to children with learning______(64).She says using music to improve listening skills could mean they______(65)sentences and understand facial expressions better. _________52
[多选题]共用题干 Musical Training Can Improve Communication SkillsAmerican scientists say musical training seems to improve communication skills and language retardation (延迟).They found that developing musical skill involves the______(51)process in the brain as learning how to speak.The scientists believe that could______(52)children with learning disabilities.Nina Krauss is a neurobiologist at Northwestern University in Illinois.She says musical training______(53)putting together different kinds of information,such as hearing music,looking at musical notes,touching an instrument and watching other musicians.This______(54)is not much different from learning how to speak.Both involve different senses.She further explains musical training and learning to______(55)each make us think about what we are doing.She says speech and music______(56)through a structure of the nervous system called the brain stem.The brain stem______(57)our ability to hear.Until recently,experts have thought the brain stem could not be developed or changed.______(58)Professor Krauss and her team found that musical training can improve a person's brain stem activity.The study involved individuals with different levels of musical______(59).They were asked to wear an electrical device that measures______(60)activity.The individuals wore the electrode while they watched a video of someone speaking and a person playing a musical instrument-the cello(大提琴).Professor Krauss says cellos have sound qualities similar______(61)some of the sounds that are impor-tant with speech.The study found that the more years of training people had,the more______(62)they were to the sound and rhythm of the music.Those who were involved in musical activities were the same people in whom the______(63)of sensory events was the strongest.It shows the importance of musical training to children with learning______(64).She says using music to improve listening skills could mean they______(65)sentences and understand facial expressions better. _________57
[多选题]共用题干 New Understanding of Natural Silk's MysteriesNatural silk,as we all know,has a strength that man-made materials have long struggled to match.In a discovery that sounds more like an ancient Chinese proverb than a materials science breakthrough,MIT re- searchers have discovered that silk gets its strength from its weakness.Or,more specifically,its many weak- nesses. Silk gets its extraordinary durability and ductility(柔韧性)from an unusual arrangement of hydrogen bonds that are intrinsically very weak but that work together to create a strong,flexible structure.Most materials一especially the ones we engineer for strength一get their toughness from brittleness.As such,natural silks like those produced by spiders have long fascinated both biologists and engineers because of their light weight,ductility and high strength(pound for pound,silk is stronger than steel and far less brittle). But on its face,it doesn't seem that silks should be as strong as they are;molecularly,they are held together by hydrogen bonds , which are far weaker than the covalent(共价的)bonds found in other molecules.To get a better understanding of how silk manages to produce such strength through such weak bonds, the MIT team created a set of computer models that allowed them to observe the way silk behaves at the atomic level. They found that the arrangement of the tiny silk nanocrystals(纳米晶体)is such that the hydro- gen bonds are able to work cooperatively,reinforcing one another against external forces and failing slowlywhen they do fail,so as not to allow a sudden fracture to spread across a silk structure.The result is natural silks that can stretch and bend while retaining a high degree of strength.But while that's all well and good for spiders,bees and the like,this understanding of silk geometry could lead to new materials that are stronger and more ductile than those we can currently manufacture.Our best and strongest materials are generally expensive and difficult to produce(requiring high temperature treatments or energy-intensive processes).By looking to silk as a model,researchers could potentially devise new manufacturing methods that rely on inexpensive materials and weak bonds to create less rigid,more forgiving materials that are nonetheless stronger than anything currently on offer. And if you thought you were going to get out of this materials science story without hearing about carbon nanotubes(纳米碳管), think again. The MIT team is already in the lab looking into ways of synthesizing silk-like structures out of materials that are stronger than natural silk-like carbon nanotubes. Super-silks are on the horizon. Biologists and engineers are interested in understanding natural silks because they are very light and brittle.
[多选题]共用题干 第二篇Students Learn Better with Touchscreen DesksObserve the criticisms of nearly any major public education system in the world,and a few of the many complaints are more or less universal.Technology moves faster than the education system.Teachers must teach at the pace of the slowest student rather than the fastest. And一particularly in the United States一 school children as a group don't care much for,or excel(擅长)at,mathemnatics. So it's heartening to learn that a new kind of"classroom of the future"shows promise at easing some of these problems,starting with that fundamental piece of classroom furniture:the desk.A UK study involving roughly 400 students,mostly aged 8一10 years,and a new generation of multis-touch,multi-user,computerized desktop surfaces is showing that over the last three years the technology has appreciably boosted students'math skills compared with peers learning the same material via the con- ventional paper-and-pencil method.How?Through collaboration,mostly,as well as by giving teachers better tools by which to micromanage individual students who need some extra instruction while allowing the rest of the class to continue moving forward.Traditional instruction still shows respectable efficacy(效力)at increasing students'fluency in mathe- matics,essentially through memorization and practice一dull,repetitive practice.But the researchers have con-cluded that these new touchscreen desks boost both fluency and flexibility一the critical thinking skills that al- low students to solve complex problems not simply through knowing formulas and devices,but by being able to figure out what the real problem is and the most effective means of stripping it down and solving it.One reason for this,the researchers say,is the multi-touch aspect of the technology.Students working in the next-gen classroom can work together at the same tabletop,each of them contributing and engaging with the problem as part of a group.Known as SynergyNet,the software uses computer vision systems that see in the infrared(红外线的)spectrum to distinguish between different touches on different parts of the surface, allowing students to access and use tools on the screen,move objects and visual aids around on their desk- tops,and otherwise physically interact with the numbers and information on their screens.By using these screens collaboratively,the researchers say,the students are to some extent teaching themselves as those with a stronger grasp on difficult concepts pull other students forward along with them. What is the benefit students get from the new tech?
[多选题]共用题干 Solar Power Without Solar CellsA dramatic and surprising magnetic effect of light discovered by University of Michigan researchers could lead to solar power without traditional semiconductor-based solar cells.The researchers found a way to make an"optical________(51)",said Stephen Rand,a professor in the departments of Electrical Engineering and Computer Science,Physics and Applied Physics.Light has electric and magnetic_______(52).Until now,scientists thought the effects of the mag-netic field were so weak that they could be________(53).What Rand and his colleagues found is that at the right intensity,when light is traveling through a material that does not_________(54)electricity,the light field can generate magnetic effects that are 100 million times stronger than previously expected.Under these circumstances,the magnetic effects develop strength_________(55)to a strong electric effect."This could lead to a new kind of solar cell without semiconductors and without absorption to produce charge separation,"Rand said."In solar cells,the_________(56)goes into a matenal,gets absorbed and creates heat.Here,we expect to have a very low heat load.Instead of the light being absorbed,energy is stored in the magnetic moment.Intense magnetization can be induced by intense light and then it is ultimately capable of providing a capacitive power________(57)."What makes this possible is a previously unde- tected brand of"optical rectification",says William Fisher,a doctoral student in applied physics.In tradi- tional optical rectification,light's electric field causes a charge separation,or a pulling_________(58)of the positive and negative charges in a material.This sets up a voltage,similar to______(59)in a battery.Rand and Fisher found that under the right circumstances and in right types of materials,the light's magnetic field can also create optical rectification.The light must be shone through a________(60)that does not conduct electricity,such as glass.And it must be focused to an intensity of 10 million watts per square centimeter. Sunlight isn't this_______(61)on its own,but new materials are being sought that would work at lower intensities,Fisher said."In our most recent paper,we show that incoherent light like sunlight is theoretically almost _________(62)effective in producing charge separation as laser light is,"Fisher said.This new_________(63)could make solar power cheaper,the researchers say.They predict that with improved materials they could achieve 10 percent efficiency in converting solar power to usable energy.That's equivalent to today's commercial-grade solar cells."To manufacture modern solar cells,you have to do. _______(64)semiconductor processing,"Fisher said."All we would need are lenses to focus the light and a fiber to guide it.Glassworks for _________ (65).It's already made in bulk,and it doesn't require as much processing.Transparent ceramics might be even better." _________(60)
[多选题]共用题干 Climate Change:The Long Reach1.Earth is warming.Sea levels are rising.There's more carbon in the air,and Arctic ice is melting faster than at any time in recorded history.Scientists who study the environment to better gauge(评估) Earth's future climate now argue that these changes may not reverse for a very long time.2.People burn fossil fuels like coal and oil for energy.That burning releases carbon dioxide,a colorless gas.In the air,this gas traps heat at Earth's surface.And the more carbon dioxide released,the more the planet warms.If current consumption of fossil fuels doesn't slow,the long-term climate impacts could last thousands of years-and be more severe than scientists had been expecting.Climatologist Richard Zeebe of the University of Hawaii at Manoa offers this conclusion in a new paper.3.Most climate-change studies look at what's going to happen in the next century or so.During that time , changes in the planet's environment could nudge(推动)global warming even higher.For example, snow and ice reflect sunlight back into space.But as these melt,sunlight can now reach-and warm-the exposed ground.This extra heat raises the air temperature even more,causing even more snow to melt.This type of rapid exaggeration of impacts is called a"fast feedback".4.Zeebe says it's important to look at fast feedbacks.However,he adds,they're limited.From a climate change perspective,"This century is the most important time for the next few generations,"he told Science News."But the world is not ending in 2100."For this new study,Zeebe now focuses on"slow feedbacks".While fast feedback events unfold over decades or centuries,slow feedbacks can take thousands of years.Melting of continental ice sheets and the migration of plant life-as they relocate to more comfortable areas-are two examples of slow feedbacks.5.Zeebe gathered information from previously published studies investigating how such processes played out over thousands of years during past dramatic changes in climate.Then he came up with a forecast for the future that accounts for both slow and fast feedback processes.Climate forecasts that use only fast feedbacks predict a 4.5 degree Celsius(8.1 degree Fahrenheit)change by the year 3000.But slow feedbacks added another 1.5℃-for a 6℃ total increase,Zeebe reports.He also found that slow feedback events will cause global warming to persist for thousands of years after people run out of fossil fuels to burn. Melting of snow and ice enables sunlight to reach______.
[单选题]Inquest told of hospital err A HOSPITAL err left a dying man on the wrong ward f two days asdeep vein thrombosis (DVT) ravaged his body, an inquest heard. Stephen MelvinNewbold suffered massive brain damage when a blood clot fmed in his veins.Now his families are considering legal action against Yk Hospital, sayingthat his death was “untimely unnecessary”. Mr Newbold, a 52-year-old maintenance wker, went to Yk Hospitalon November 3 complaining of a swollen right foot. He should have been sent toa surgical ward he would have been treated with1 Fragmin, a drug whichcounters the effects of DVT. However, hospital staff wrongly admitted him to2an thopedic ward, he stayed f two days, befe finally beingtransferred to the care of a consultant vascular surgeon. Twenty-four hourslater, on November 6, docts decided they would have to operate to remove hisleg below the knee. The operation went ahead on November 10, but two days later MrNewbold suffered a cardiac arrest. A scan revealed he had had a pulmonaryembolism, a condition related to DVT. Mr Newbold suffered brain damage diedin the hospital on November 16. Giving evidence, the surgeon said he could not explain why MrNewbold had been admitted to an thopedic ward it was not policy toadminister Fragmin. He did not know why his medical team had not given MrNewbold the drug later. Yk coner Donald Coverdale said, “From November 3until the day of the operation, no Fragmin was given to Mr Newbold. If he hadbeen admitted to a consultant vascular surgeon’s care from day one,it is clear that Fragmin would have been prescribed. Fragmin reduces the riskof DVT, but does not eliminate it. It is impossible to say whether Mr Newboldwould have suffered this DVT if he had received the Fragmin.” He recded averdict of death by misadventure. Kim Daniells, Mr Newbold’s family’s lawyer,said, “The family hope that the hospital will learn from the errs, that no other families will have to suffer in the future.” A spokeswoman f Yk Hospital’s NHS Trust said, “We wouldlike to extend our sincere sympathies to the family of Stephen Newbold duringthis difficult time.”   词汇: ward n.病房 vein n.血管 thrombosis n.血栓 clot n.凝块 maintenance n.维修,维护 Fragmin n.法安明(又名片段化蛋白) staff n.员工;职工 consultant n.顾问,咨询,会诊医师 surgeon n.心血管外科顾问 knee n.膝盖 embolism n.栓塞;栓塞形成 verdict n.裁决 misadventure n.灾难,不幸遭遇,意外事故 sympathy n.同情   注释: 1.be treated with...被用......药物进行治疗 2.be admitted to...被收容至,被移送至(本文中是“被送至病房”)   练习: 7.Mr Newbold’s family’s lawyer was not qualified.
[多选题]共用题干 第一篇Forecasting MethodsThere are several different methods that can be used to create a forecast. The method a forecaster chooses depends upon the experience of the forecaster,the amount of information available to the forecaster,the level of difficulty that the forecast situation presents,and the degree of accuracy or confidence needed in the forecast.The first of these methods is the persistence method,the simplest way of producing a forecast.The per- sistence method assumes that the conditions at the time of the forecast will not change.For example,if it is sunny and 87 degrees today,the persistence method predicts that it will be sunny and 87 degrees tomorrow. If two inches of rain fell today,the persistence method would predict two inches of rain for tomorrow. However,if weather conditions change significantly from day to day,the persistence method usually breaks down and is not the best forecasting method to use.The trends method involves determining the speed and direction of movement for fronts,high and low pressure centers , and areas of clouds and precipitation(降水量).Using this information , the forecaster can predict where he or she expects those features to be at some future time.For example,if a storm system is 1,000 miles west of your location and moving to the east at 250 miles per day,using the trends method you would predict it arrive in your area in 4 days.The trends method works well when systems continue to move at the same speed in the same direction for a long period of time.If they slow down,speed up,change intensi- ty,or change directions,the trends forecast will probably not work as well.The climatology(气候学)method is another simple way of producing a forecast. This method involves averaging weather statistics accumulated over many years to make the forecast.For example,if you were using the climatology method to predict the weather for New York City on July 4th,you would go through all the weather data that has been recorded for every July 4th and take an average.The climatology method oniy works well when the weather pattern is similar to that expected for the chosen time of year. If the pattern is quite unusual for the given time of year,the climatology method will often fail.The analog method is a slightly more complicated method of producing a forecast.It involves examining today's forecast scenario(模式)and remembering a day in the past when the weather scenario looked very similar(an analog).The forecaster would predict that the weather in this forecast will behave the same as ii did in the past.The analog method is difficult to use because it is virtually impossible to find a predict ana- log.Various weather features rarely align themselves in the same locations as they were in the previous time. Even small differences between the current time and the analog can lead to very different results. The trends method works well when_________.
[多选题]共用题干 Solar Power Without Solar CellsA dramatic and surprising magnetic effect of light discovered by University of Michigan researchers could lead to solar power without traditional semiconductor-based solar cells.The researchers found a way to make an"optical________(51)",said Stephen Rand,a professor in the departments of Electrical Engineering and Computer Science,Physics and Applied Physics.Light has electric and magnetic_______(52).Until now,scientists thought the effects of the mag-netic field were so weak that they could be________(53).What Rand and his colleagues found is that at the right intensity,when light is traveling through a material that does not_________(54)electricity,the light field can generate magnetic effects that are 100 million times stronger than previously expected.Under these circumstances,the magnetic effects develop strength_________(55)to a strong electric effect."This could lead to a new kind of solar cell without semiconductors and without absorption to produce charge separation,"Rand said."In solar cells,the_________(56)goes into a matenal,gets absorbed and creates heat.Here,we expect to have a very low heat load.Instead of the light being absorbed,energy is stored in the magnetic moment.Intense magnetization can be induced by intense light and then it is ultimately capable of providing a capacitive power________(57)."What makes this possible is a previously unde- tected brand of"optical rectification",says William Fisher,a doctoral student in applied physics.In tradi- tional optical rectification,light's electric field causes a charge separation,or a pulling_________(58)of the positive and negative charges in a material.This sets up a voltage,similar to______(59)in a battery.Rand and Fisher found that under the right circumstances and in right types of materials,the light's magnetic field can also create optical rectification.The light must be shone through a________(60)that does not conduct electricity,such as glass.And it must be focused to an intensity of 10 million watts per square centimeter. Sunlight isn't this_______(61)on its own,but new materials are being sought that would work at lower intensities,Fisher said."In our most recent paper,we show that incoherent light like sunlight is theoretically almost _________(62)effective in producing charge separation as laser light is,"Fisher said.This new_________(63)could make solar power cheaper,the researchers say.They predict that with improved materials they could achieve 10 percent efficiency in converting solar power to usable energy.That's equivalent to today's commercial-grade solar cells."To manufacture modern solar cells,you have to do. _______(64)semiconductor processing,"Fisher said."All we would need are lenses to focus the light and a fiber to guide it.Glassworks for _________ (65).It's already made in bulk,and it doesn't require as much processing.Transparent ceramics might be even better." _________(53)
[多选题]共用题干 第一篇The Northern LightsThe sun is stormy and has its own kind of weather.It is so hot and active that even the Sun's gravity cannot hold its atmosphere in check!Energy flows away from the Sun toward the Earth in a stream of electrified particles that move at speeds around a million miles per hour.These particles are called plasma (等离子体),and the stream of plasma coming from the Sun is called the solar wind.The more active the Sun,the stronger the solar wind.The solar wind constantly streams toward the Earth,but don't worry because a protective magnetic field surrounds our planet.The same magnetic field that makes your compass point north also steers the particles from the Sun to the north and south poles.The charged particles become trapped in magnetic belts around the Earth.When a large blast of solar wind crashes into the Earth's magnetic field,the magnetic field first gets squeezed and then the magnetic field lines break and reconnect.The breaking and reconnecting of the magnetic field lines can cause atomic particles called electrons trapped in the belts to fall into tile Earth's atmosphere at the poles.As the electrons fall to the Earth,they collide with gas molecules in the atmosphere,creating flashes of light in the sky.Each atmospheric gas glows a different color.Oxygen and nitrogen glows red and green arid nitrogen glows violet purple.As these various colors glow and dance in the night sky,they create the Northern Lights and the Southern Lights.Watching auroras(北极光)is fun and exciting, but normally you can only see them in places far north like Alaska and Canada.The movement of the aurora across the sky is usually slow enough to easily follow with your eyes but they can also pulsate(跳动),flicker(闪烁),or even move like waves.During solar maximum,5 auroras are seen as far south as Florida,even Mexico!Auroras often seem to be very close to the ground,but the lowest aurora is still about 100 kilometers above the ground,a distance much higher than clouds are formed or airplanes can fly.A typical aurora band can be thousands of kilometers long,a few hundred kilometers high,but only a few hundred meters thick.We hope you are able to travel to far north places like the Arctic Circle and see the Northern Lights at least once during your lifetime.We know you will never forget it! What is the author's tone toward the Northern Lights?
[多选题]共用题干 第二篇The Mir Space StationThe Russian Mir Space Station,which came down in 2001 at last after 15 years of pioneering the concept of long-term human space flight,is remembered for its accomplishments in the human space flight history.It can be credited with many firsts in space.During Mir's lifetime,Russia spent about US $4.2 billion to build and maintain the station.The Soviet Union launched Mir,which was designed to last from three to five years,on February 20, 1986,and housed 104 astronauts over 12 years and seven months,most of whom were not Russian.In fact, it became the first international space station by playing host to 162 people from 1 1 countries.From 1995 through 1998,seven astronauts from the United States took turns living on Mir for up to six months each.They were among the 37 Americans who visited the station during nine stopovers by space shuttles.The more than 400 million the United States provided Russian for the visits not only kept Mir operating,but also gave the Americans and their partners in the international station project valuable experience in long-term flight and multinational operations.A debate continues over Mir's contributions to science.During its existence,Mir was the laboratory for 23,000 experiments and carried scientific equipment,estimated to be worth $80 million,from many nations.Experiments on Mir are credited with a range of findings,from the first solid measurement of the ration of heavy helium(氦)atoms in space to how to grow wheat in space.But for those favouring human space exploration,Mir showed that people could live and work in space long enough for a trip to Mars.The longest single stay in space is the 437.7 days that Russian astronaut Valery Polyakov spent on Mir from 1994 to 1995.And Sergie Avdeyev accumulated 747.6 days in space in three trips to the space station.The longest American stay was that of Shannon Lucid,who spent 188 days aboard Mir in 1996.Despite the many firsts Mir accomplished,1997 was a bad year out of 15 for Mir.In 1997,an oxygen generator caught fire.Later,the main computer system broke down,causing the station to drift several times and there were power failures.Most of these problems were repaired,with American help and suppliers,but Mir's reputation as a space station was ruined.Mir's setbacks are nothing,though,when we compare them with its accomplishments.Mir was a tremendous success,which will be remembered as a milestone in space exploration and the space station that showed long-term human habitation in space was possible.But it's time to move on to the next generation.The International Space Station being built will be better,but it owes a great debt to Mir. It can be inferred from the last paragraph that______.
[单选题]The Sahara Desert is the largest desert in the wld. It stretchesacross Africa from Senegal to Egypt. The Sahara Desert is an unfriendlyenvironment. During the day it's very hot, at night it’s sometimesvery cold. It is also difficult to find water in the Sahara. In 2006, Kevin Lin, Ray Zahab, Charlie Engle decided to dosomething very difficult. They made the decision to run across the SaharaDesert 4,300 miles (6,920km). It seemed impossible to do, but they wanted to try.The three men liked to test themselves, this would be a very big test. On the mning of November 2, Kevin, Ray, Charlie started theirtrip across the Sahara. Every mning they began running at 5:00. At11 a.m.they stopped rested until 5 p.m. Then they ran again until 9:30 in theevening. Each day they ran about 40 miles (64 km). Every day it was the samething. They got up ran. They listened to music on their iPods, they ran ran. Kevin, Ray, Charlie needed to eat a lot of food during theirtrip. Most people need about 2,000 calies of food each day. Kevin, Ray, Charlie needed between 6,000 9,000 calies every day. That's a lot offood! They also needed to drink a lot of water. The three men had some problems on their trip, many times theywanted to quit go home. It was often very hot (140°F/60°C) duringthe day, the heat made them sick. Their legs feet hurt. Sometimes itwas very windy, they couldn't see. One time they got lost. But they didn'tquit. After 111 days, Kevin, Ray; Charlie successfully finished their tripacross the Sahara Desert. They hugged each other put their hs in thewater of the Red Sea. Then they ran to a hotel to take a long shower.   词汇: stretch v. 延伸,伸展 calie n. 卡(路里),小卡,大卡 quit v. 停止,放   注释: 1. ... made the decision to run across ...:......决正跑步横跨......   练习:2. Each day the men ran f approximately eight hours.
[多选题]共用题干 Musical Training Can Improve Communication SkillsAmerican scientists say musical training seems to improve communication skills and language retardation (延迟).They found that developing musical skill involves the______(51)process in the brain as learning how to speak.The scientists believe that could______(52)children with learning disabilities.Nina Krauss is a neurobiologist at Northwestern University in Illinois.She says musical training______(53)putting together different kinds of information,such as hearing music,looking at musical notes,touching an instrument and watching other musicians.This______(54)is not much different from learning how to speak.Both involve different senses.She further explains musical training and learning to______(55)each make us think about what we are doing.She says speech and music______(56)through a structure of the nervous system called the brain stem.The brain stem______(57)our ability to hear.Until recently,experts have thought the brain stem could not be developed or changed.______(58)Professor Krauss and her team found that musical training can improve a person's brain stem activity.The study involved individuals with different levels of musical______(59).They were asked to wear an electrical device that measures______(60)activity.The individuals wore the electrode while they watched a video of someone speaking and a person playing a musical instrument-the cello(大提琴).Professor Krauss says cellos have sound qualities similar______(61)some of the sounds that are impor-tant with speech.The study found that the more years of training people had,the more______(62)they were to the sound and rhythm of the music.Those who were involved in musical activities were the same people in whom the______(63)of sensory events was the strongest.It shows the importance of musical training to children with learning______(64).She says using music to improve listening skills could mean they______(65)sentences and understand facial expressions better. _________62
[多选题]共用题干 Underground Coal FiresCoal burning deep underground in China,India and Indonesia is threatening the environment and human life , scientists have warned.These large-scale______(51)blazes(火焰)cause the ground temperature to heat up and kill surrounding vegetation,produce greenhouse gases and can______(52) ignite(点燃)forest fires , a group of scientists told the annual meeting of the American Association for theAdvancement of Science in Denver.The resulting______(53)of poisonous elements like mercury can also pollute local water sources and soils,they warned."Coal fires are a global disaster,"said Associate Professor Glenn Stracher of East Georgia College inSwainsboro,USA.But______(54)few people know about them.Coal can heat up on its own,and eventually catch fire and bum,if there is a continuous oxygen supply.The heat produced is not caused to______(55)and under the right combinations of sunlight and oxygen,can trigger spontaneous(自发的)catching fire and buming.This can occur underground , in coal stockpiles, abandoned mines or even as coal is transported.______(56)fires in China consume up to 200 million tons of coal per year,delegates were told.In______(57),the U.S.economy consumes about one billion tons of coal annually,said Stracher,______(58)analysis of the likely impact of coal fires has been accepted for publication in the International Journal of Coal Ecology.______(59)underway,coal fires can bum for decades,even centuries.In the process,they release large______(60)of greenhouse gases,poisonous fumes and black particles into the atmosphere.The members of the panel discussed the______(61)these fires may be having on global and regional climate change,and agreed that the underground nature of the fires makes them difficult to______(62).Ultimately,the remote sensing and other techniques should allow scientists to______(63)how much carbon dioxide these fires are emitting(释放).One suggested______(64)of containing the fires was presented by Gary Colaizzi,of the engineering firm Goodson,which has developed a heat-resistant grout(灌浆),which is designed to be pumped into the coal fire to______(65)the oxygen supply. _________55
[多选题]共用题干 第一篇Forecasting MethodsThere are several different methods that can be used to create a forecast. The method a forecaster chooses depends upon the experience of the forecaster,the amount of information available to the forecaster,the level of difficulty that the forecast situation presents,and the degree of accuracy or confidence needed in the forecast.The first of these methods is the persistence method,the simplest way of producing a forecast.The per- sistence method assumes that the conditions at the time of the forecast will not change.For example,if it is sunny and 87 degrees today,the persistence method predicts that it will be sunny and 87 degrees tomorrow. If two inches of rain fell today,the persistence method would predict two inches of rain for tomorrow. However,if weather conditions change significantly from day to day,the persistence method usually breaks down and is not the best forecasting method to use.The trends method involves determining the speed and direction of movement for fronts,high and low pressure centers , and areas of clouds and precipitation(降水量).Using this information , the forecaster can predict where he or she expects those features to be at some future time.For example,if a storm system is 1,000 miles west of your location and moving to the east at 250 miles per day,using the trends method you would predict it arrive in your area in 4 days.The trends method works well when systems continue to move at the same speed in the same direction for a long period of time.If they slow down,speed up,change intensi- ty,or change directions,the trends forecast will probably not work as well.The climatology(气候学)method is another simple way of producing a forecast. This method involves averaging weather statistics accumulated over many years to make the forecast.For example,if you were using the climatology method to predict the weather for New York City on July 4th,you would go through all the weather data that has been recorded for every July 4th and take an average.The climatology method oniy works well when the weather pattern is similar to that expected for the chosen time of year. If the pattern is quite unusual for the given time of year,the climatology method will often fail.The analog method is a slightly more complicated method of producing a forecast.It involves examining today's forecast scenario(模式)and remembering a day in the past when the weather scenario looked very similar(an analog).The forecaster would predict that the weather in this forecast will behave the same as ii did in the past.The analog method is difficult to use because it is virtually impossible to find a predict ana- log.Various weather features rarely align themselves in the same locations as they were in the previous time. Even small differences between the current time and the analog can lead to very different results. Historical weather data are necessary in_________.
[多选题]共用题干 第三篇A New Strategy to Overcome Breast CancerPost-menopausal(绝经后的)women who walk for an hour a day can cut their chance of breast cancersignificantly,a study has suggested.The report,which followed 73,000 women for 17 years,found walking for at least seven hours a week lowered the risk of the disease.The American Cancer Society team said this was the first time reduced risk was specifically linked to walking.UK experts said there was more evidence that lifestyle influenced cancer risk.A recent poll for the charity Ramblers found a quarter of adults walk for no more than an hour a week, but being active is known to reduce the risk of a number of cancers.This study,published in CancerEpidemiology,Biomarkers&Prevention,followed 73,615 women out of 97,785 aged 50-74 who had been recruited by the American Cancer Society between 1992 and 1993,so it could monitor the incidence of cancer in the group.They were asked to complete questionnaires on their health and on how much time they were active and participating in activities such as walking, swimming and aerobics(有氧运动)and how much time they spentsitting watching television or reading.They completed the same questionnaires at two-year intervals between 1997 and 2009.Of the women,47%said walking was their only recreational activity.Those who walked for at least seven hours per week had a 14%lower risk of breast cancer compared to those who walked three or fewer hours per week.Dr.Alpa Patel,a senior epidemiologist at the American Cancer Society in Atlanta,Georgia,who led the study,said:"Given that more than 60%of women report some daily walking,promoting walking as ahealthy leisure-time activity could be an effective strategy for increasing physical activity amongst post-menopausal women.We were pleased to find that without any other recreational activity,just walking one hour a day was associated with a lower risk of breast cancer in these women."" More strenuous(紧张的)and longer activities lowered the risk even more."Baroness Delyth Morgan,chief executive of Breast Cancer Campaign,said:"This study adds further evidence that our lifestyle choices can play a part in influencing the risk of breast cancer and even small changes incorporated into our normal day-to-day activity can make a difference."She added:"We know that the best weapon to overcoming breast cancer is the ability to stop it occurring in the first place.The challenge now is how we turn these findings into action and identify other sustainable lifestyle changes that will help us prevent breast cancer." The word"sustainable"in the last paragraph is closest in meaning to______.
[多选题]共用题干 第二篇Download Knowledge Directly to Your BrainFor the first time,researchers have been able to hack into the process of learning in the biain,using induced brain patterns to create a learned behavior. It's not quite as advanced as an instant Kung-fu down- load,and it's not as sleek as cognitive inception,but it's still an important finding that could lead to new teaching and rehabilitation techniques.Future therapies could decode the brain activity patterns of an athlete or a musician,and use them as a benchmark for teaching another person a new activity,according to the researchers.Scientists from Boston University and ATR Computational Neuroscience Laboratories in Kyoto used functional magnetic resonance imaging,or fMRI,to study the learning process.They were examining the adult brain's aptitude for visual perceptual learning,or VPL,in which repetitive training improves a per- son's performance on a particular task.Whether adults can do this as well as young people has been an on- going debate in neuroscience.Led by BU neuroscientist Takeo Watanabe,researchers used a method called decoded fMRI neurofeed- back to stimulate the visual cortex.First they showed participants circles at different orientations.Then they used fMRI to watch the participants'brain activity.The researchers were then able to train the participants to recreate this visual cortex activity.The volunteers were again placed in MRI machines and asked to visualize shapes of certain colors.The participants were asked to"somehow regulate activity in the posterior part of the brain"to make a solid green disc as large as they could.They were told they would get a paid bonus proportional to the size of this disc, but they weren't told anything about what the disc meant.The researchers watched the participants'brain activity and monitored the activation patterns in their visual cortices."Participants can be trained to control the overall mean activation of an entire brain region,"the study authors write,"or the adtivation in one region relative to that in another region."This worked even when test subjects were not aware of what they were learning,the researchers said."The most surprising thing in this study is that mere inductions of neural activation patterns corresponding to a specific visual feature led to visual performance improvement on the visual feature,without presenting the fea- ture or subjects' awareness of what was to be learned,"Watanabe said in a statement.Watanabe and colleagues said this method can be a powerful tool."It can'incept' a person to acquire new learning, skills,or memory,or possibly to restore skills or knowledge that has been damaged through accident,disease,or aging,without a person's awareness of what is learned or memorized,"they write. Who are most likely to benefit from the study?
[多选题]共用题干 Solar Power Without Solar CellsA dramatic and surprising magnetic effect of light discovered by University of Michigan researchers could lead to solar power without traditional semiconductor-based solar cells.The researchers found a way to make an"optical________(51)",said Stephen Rand,a professor in the departments of Electrical Engineering and Computer Science,Physics and Applied Physics.Light has electric and magnetic_______(52).Until now,scientists thought the effects of the mag-netic field were so weak that they could be________(53).What Rand and his colleagues found is that at the right intensity,when light is traveling through a material that does not_________(54)electricity,the light field can generate magnetic effects that are 100 million times stronger than previously expected.Under these circumstances,the magnetic effects develop strength_________(55)to a strong electric effect."This could lead to a new kind of solar cell without semiconductors and without absorption to produce charge separation,"Rand said."In solar cells,the_________(56)goes into a matenal,gets absorbed and creates heat.Here,we expect to have a very low heat load.Instead of the light being absorbed,energy is stored in the magnetic moment.Intense magnetization can be induced by intense light and then it is ultimately capable of providing a capacitive power________(57)."What makes this possible is a previously unde- tected brand of"optical rectification",says William Fisher,a doctoral student in applied physics.In tradi- tional optical rectification,light's electric field causes a charge separation,or a pulling_________(58)of the positive and negative charges in a material.This sets up a voltage,similar to______(59)in a battery.Rand and Fisher found that under the right circumstances and in right types of materials,the light's magnetic field can also create optical rectification.The light must be shone through a________(60)that does not conduct electricity,such as glass.And it must be focused to an intensity of 10 million watts per square centimeter. Sunlight isn't this_______(61)on its own,but new materials are being sought that would work at lower intensities,Fisher said."In our most recent paper,we show that incoherent light like sunlight is theoretically almost _________(62)effective in producing charge separation as laser light is,"Fisher said.This new_________(63)could make solar power cheaper,the researchers say.They predict that with improved materials they could achieve 10 percent efficiency in converting solar power to usable energy.That's equivalent to today's commercial-grade solar cells."To manufacture modern solar cells,you have to do. _______(64)semiconductor processing,"Fisher said."All we would need are lenses to focus the light and a fiber to guide it.Glassworks for _________ (65).It's already made in bulk,and it doesn't require as much processing.Transparent ceramics might be even better." _________(62)
[多选题]共用题干 Europa's Watery UnderworldEuropa,one of Jupiter's 63 known moons,looks bright and icy on the surface.But appearances can be deceiving:Miles within its cracked,frigid shell,Europa probably hides giant pools of liquid water. Where scientists find liquid water,they hope to find life as well.Since we can't go diving into Europa's depths just yet,scientists instead have to investigate the moon's surface for clues to what lies beneath.In a new study,scientists investigated one group of strange ice patterns on Europa and concluded that the formations mark the top of an underground pool that holds as much water as the U.S.Great Lakes.Pictures of Europa,which is slightly smaller than Earth's moon,clearly show a tangled,icy mishmash of lines and cracks known as"chaos terrains".These chaotic places cover more than half of Europa. For more than 10 years,scientists have wondered what causes the formations.The new study suggests that they arise from the mixing of vast underground stores of liquid water with icy material near the surface.For scientists who suspect that Europa also may be hiding life beneath its icy surface,the news about the new lake is exciting."It would be great if these lakes harbored life,"Britney Schmidt,a planetary scientist who worked onthe study,told Science News."But even if they didn't,they say that Europa is doing something interesting and active right now."Schmidt,a scientist at the University of Texas at Austin,and her colleagues wanted to know how chaos terrains form.Since they couldn't rocket to Europa to see for themselves,they searched for similar forma- tions here on Earth.They studied collapsed ice shelves in Antarctica and icy caps on volcanoes in Iceland. Those features on Earth formed when liquid water mixed with ice.The scientists now suspect something similar might be happening on Europa:that as water and ice of different temperatures mingle and shift,the surface fractures.This would explain the jumbled ice sculptures."Fracturing catastrophically disrupts the ice in the same way that it causes ice shelves to collapse on Earth,"Schmidt told Science News.She and her team found that the process could be causing chaos terrains to form quickly on Europa.The new study suggests that on this moon,elements such as oxygen from the surface blend with the deep bodies of water. That mixture may create an environment that supports life. The strange ice patterns on Europa are formed as a result of a mixture of liquid water and solid material underground water pool.
[多选题]共用题干 Better Solar Energy Systems:More Heat,More LightSolar photovoltaic(光电的)thermal energy systems , or PVTs , generate both heat and electricity , but _________ (51)now they haven't been very good at the heat-generating part compared to a stand-alone solar thermal collector. That ' s because they operate at low temperatures to cool crystalline silicon(晶体硅)solar cells, _______(52)lets the silicon generate more electricity but isn't a very efficient way to gather heat.That's a problem of economics.Good solar hot-water systems can harvest much more energy than asolar一electric system at a substantially lower _________(53).And it's also a space problem:photovoltaiccells can_________(54)up all the space on the roof,leaving little room for thermal applications.In a pair of studies,Joshua Pearce,an associate professor of materials science and engineering,has de- vised a_________(55)in the form of a better PVT made with a different kind of silicon.Most solar panels are made with crystalline silicon,but you can also make solar cells out of amorphous(非晶形的)silicon , commonly known________( 56 ) thin-film silicon. They don ' t create as much elec-tricity,but they are lighter,flexible,and cheaper. And,because they________(57)much less silicon,they have a greener footprint._________(58),thin-film silicon solar cells are vulnerable to some bad一news physics in the form of the Staebler-Wronski effect."That means that their efficiency drops when you_________(59)them to light一pretty much the worst possible effect for a solar cell,"Pearce explains,which is one of the__________(60)thin-film solar panels make up only a small fraction of the market.However,Pearce and his team found a_______(61)to engineer around the Staebler-Wronski effect by incorporating thin-film silicon in a new________(62)of PVT. You don't have to cool down thin-film sili- con to make it work.In fact,Pearce's group discovered that by heating it to solar-thermal operating tempera- tures,near the boiling_________(63)of water,they could make thicker cells that largely_________(64) the Staebler-Wronski effect.When they applied the thin-film silicon directly to a solar thermal energy collector, they also found that by baking the cell once a day,they_________(65)the solar cell's electrical efficiency by over 10 percent. _________(57)
[单选题]第二十二篇 RealWld Robots   When you think of a robot, do you envision ashiny, metallic device having the same general shape as a human being,perfming humanlike functions, responding to your questions in a monotonevoice accentuated by high-pitched tones beeps? This is the way many of usimagine a robot, but in the real wld, a robot is not humanoid at all. Insteada robot often is a voiceless, box-shaped machine that efficiently carries outrepetitive dangerous functions usually perfmed by humans. Today’s robot is me than an automatic machine that perfms one taskagain again. A modern robot is programmed with varying degrees ofartificial intelligence—that is, a robot contains acomputer program that tells it how to perfm tasks associated with human intelligence,such as reasoning, drawing conclusions, learning from past experience.   A robot does not possess a human shape fthe simple reason that a two-legged robot has great difficulty remainingbalanced. A robot does, however, move from place to place on wheels axlesthat roll rotate. A robot even has limbs that swivel move incombination with ts mots. To find its way in its surroundings1, arobot utilizes various built-in senss. Antennae attached to the robot’s base detect anything they bump into. If the robot starts to teeteras it moves on an incline, a gyroscope a pendulum inside it senses thevertical differential. To determine its distance from an object how quicklyit will reach the object,the robot bounces beams oflaser light ultrasonic sound waves off obstructions in its path2. These other senss constantly feed infmation to the computer, which then analyzesthe infmation crects adjusts the robot’sactions. As science technology advance, the robot too will progress in itsfunctions use of artificial-intelligence programs.   词汇:   envision v. 想象,预想   device n. 装置   accentuate v. 强调,重读   artificial intelligence n. 人工智能   limb n. 臂   antennae n. 天线   incline v. 倾斜   pendulum n. 钟摆   ultrasonic adj. 超声的   metallic adj. 金属的   monotone n. 单调的   humanoid adj. 像人的   axle n. 轮轴   rotate v. 旋转   swivel n. 旋转   teeter v. 摇晃   gyroscope n. 陀螺仪,回转仪   vertical n. 直立的   注释:   1.To find its way in its surroundings...:为了在周围找到路……   2.the robot bounces beams of laser light ultrasonic sound waves off obstructions in its path:机器人发射激光束和超声波,反射到障碍物上(以此来探知路径)。  练习: 4.The writer begins the passage by comparing
[多选题]共用题干 The Mysteries of NazcaIn the desert of Peru,300 kilometers from Lima,one of the most unusual artworks in the world has mystified(迷惑)people for decades._________ (46 ) But from high above,these marks are huge images of birds,fish,seashells,all beautifully carved into the earth.The Nazca lines are so difficult to see from the ground that they weren't discovered until the 1930s, when pilots spotted them while flying over the area. In all,there are about 70 different human and animal figures on the plain,along with 900 triangles,circles,and lines.Researchers have figured out that the lines are at least 1,500 years old,but their purpose is still a mystery.__________(47)However,it would probably be very tricky to land a spaceship in the middle ofpictures of dogs and monkeys.In the 1940s,an American explorer named Paul Kosok suggested that the drawings are a chronicle(记 录)of the movement of the stars and planets._________(48)Later,an astronomer tested his theory with a computer,but he couldn' t find any relation between the lines and movements in space.Another explanation is that the lines may have been made for religious reasons.British researcher Tony Morrison investigated the customs of people in the Andes Mountain and learned that they sometimes pray by the side of the road.It's possible that in the past,the lines of Nazca were created for a similar purpose. _________(49)But the local people have never constructed anything this big.Recently,two other scientists,David Johnson and Steve Mabee,have speculated that lines could have been related to water. Nazca is one of the driest places in the world and receives only 2cm of rain every year. While Johnson was searching for ancient water sources in the area,he noticed that some waterways built by ancient people were connected with the lines.Johnson believes that the Nazca lines are a giant map of the underground water in the area._________(50) _________(49)
[多选题]共用题干 Toads are Arthritic and in PainArthritis(关节炎)is an illness that can cause pain and swelling in your bones. Toads(蟾蜍),a big problem 'in the north of Australia,are suffering from painful arthritis in their legs and backbone,a new stu街has shown. The toads that jump the fastest are more likely to be larger and to have longer legs.______(46)The large yellow toads,native to South and Central America,were introduced into the north-eastern Aus- tralian state of Queensland in 1935 in an attempt to stop beetles and other insects from destroying sugarcane crops.Now up to 200 million of the poisonous toads exist in the country,and they are rapidly spreading through the state of Northern Territory at a rate of up to 60 km a year. The toads can now be found across more than one million square kilometres.________(47)A Venezuelan poison virus was tried in the 1990s but had to be abandoned after it was found to also kill native frog species.The toads have severely affected ecosystems in Australia. Ariinials,arid sometimes pets,that eat the toads die im- mediately from their poison,and the toads themselves eat anything they can fit inside their mouth._________(48)A co-author of the new study,Rick Shine,a professor at the University of Sydney,says that little atten- tion has been given to the problems that toads face.Rick and his colleagues studied nearly 500 toads from Queensland and the Northern Territory and found that those in the latter state were very different.They were active,sprinting down roads and breeding quickly.According to the results of the study,the fastest toads travel nearly one kilometre a night._________(49) But speed and strength come at a price一arthritis of the legs and backbone due to constant pressure placed on them.In laboratory tests,the researchers found that after about 15 minutes of hopping,arthritic toads wouldtravel less distance with each hop(跳跃).________(50)These toads are so programmed to move, apparently,that even when in pain the toads travelled as fast and as far as the healthy ones,continuing their constant march across the landscape. __________(48)
[多选题]共用题干 第三篇Eye-tracker Lets You Drag and Drop Files with a GlanceBored of using a mouse?Soon you'11 be able to change stuff on your computer screen-and then move it directly onto your smartphone or tablet(平板电脑)-with nothing more than a glance.A system called EyeDrop uses a head-mounted eye tracker that simultaneously records your field of view so it knows where you are looking on the screen.Gazing at an object-a photo,say-and then pressing a key,selects that object.It can then be moved from the screen to a tablet or smartphone just by glancing at the second device,as long as the two are connected wirelessly."The beauty of using gaze to support this is that our eyes naturally focus on content that we want toacquire,"says Jayson Turner,who developed the system with colleagues at Lancaster University,UK.Turner believes EyeDrop would be useful to transfer an interactive map or contact information from a public display to your smartphone or tablet for sharing photos.A button needs to be used to select the object you are looking at otherwise you end up with the"Midas touch"(点石成金)effect, whereby everything you look at gets selected by your gaze, says Turner."Imagine if your mouse clicked on everything it pointed at,"he says.Christian Holz,a researcher in human-computer interaction at Yahoo Labs in Sunnyvale,California, says the system is a nice take on getting round this fundamental problem of using gaze-tracking to interact."EyeDrop solves this in a slick(灵巧的)way by combining it with input on the touch devices we carry with us most of the time anyway and using touch input as a clutching mechanism,"he says."This now allows users to seamlessly(无缝地)interact across devices far and close in a very natural manner."While current eye-trackers are rather bulky,mainstream consumer devices are not too far away.Swedish firm Tobii is developing gaze-tracking technology that can be installed in laptops and tablets and is expected to be available to buy next year.And the Google Glass headset is expected to include eye-tracking in the future.Turner says he has also looked at how content can be cut and pasted or drag-and-dropped using a mix of gaze and taps on a touchscreen.The system was presented at the Conference on Mobile and Ubiquitous Multimedia in Sweden,last week. What is Turner likely to study next?
[多选题]共用题干 Learn About Noble Gases(惰性气体)1 Have you ever ridden on a balloon?Many tourist spots offer balloon rides in order for people to see the beauty of a place from above.A balloon contains a noble gas called helium(氦).Formerly,balloons con- tamned hydrogen but hydrogen is very flammable and dangerous when uncontrolled.Therefore,people shiftedto helium,which is safer. Helium is safe because it has the properties of the noble gases.2 People once believed that noble gases couldn't chemically react at all.For this reason,they were called inert gases(隋性气体).They were also listed under Group 0 in the old periodic table because scien- tists believed that the gases have zero valence(价)electrons in their outer shell.This was later proven to be untrue when some noble gas compounds were discovered.3 The gases are elements,which share similar properties.These properties include being monoatomic, colorless,odorless,being able to conduct electricity,and having low chemical reactivity.Noble gases include helium,neon,argon,krypton,xenon and radon.These are all found in Group 18,in the right most column of the periodic table.If you look at the periodic table,you will notice that these elements are the only ones which do not have a charge. Helium has the lowest molecular(分子的)weight while radon is theheaviest.4 Remember that chemical reactions occur because atoms have valence electrons,which are electrons in their outer shell.When the outer shell is"unfilled"or the required number of electrons is not yet com- plete,the atom is more reactive.Noble gases have a full outer shell,meaning that they have complete elec- trons in their outer shell.This complete number varies.For instance,the outer shell of helium has 2 valence electrons while the outer shell of xenon has 8 electrons.Nowadays,there remains to be a few noble gases because of the low chemical reactivity of these said gases.5 because of their properties,noble gases have many important applications.They are widely used in medicine and industries. For instance , liquid helium is used for superconducting magnets(磁体).These magnets are very important in physics and medicine.When a doctor suspects that a person's brain has been damaged,he might request for Magnetic Resonance Imaging(MRI).MRI allows the doctor to"see"the brain,without operating on the patient. Paragraph 5__________
[多选题]共用题干 第一篇Gross National HappinessIn the last century,new technology improved the lives of many people in many countries.However,one country resisted these changes.High in the Himalayan mountains of Asia,the kingdom of Bhutan remained separate. Its people and Buddhist(佛教)culture had not been affected for almost a thousand years. Bhutan, however,was a poor country.People died at a young age.Most of its people could not read,and they did notknow much about the outside world.Then,in 1972,a new ruler named King Jigme Singye Wangchuck de- cided to help Bhutan to become modern,but without losing its traditions.King Wangchuck looked at other countries for ideas.He saw that most countries measured their progress by their Gross National Product(GNP).The GNP measures products and money. When the number of products sold increases,people say the country is making progress.King Wangchuck had a different idea for Bhutan.He wanted to measure his country's progress by people's happiness.If the people's happiness increased,the king could say that Bhutan was making progress.To decide if people were happier,he created a measure called Gross National Happiness(GNH).GNH is based on certain principles that create happiness.People are happier if they have health care,education,and jobs.They are happier when they live in a healthy,protected environment.They are happier when they can keep their traditional culture and customs.Finally,people are happier when they have agood,stable government.Now there is some evidence of increased GNH in Bhutan.People are healthier and are living longer. More people are educated and employed.Twenty-five percent of the land has become national parks,and the country has almost no pollution.The Bhutanese continue to wear their traditional clothing and follow their ancient Buddhist customs.Bhutan has also become a democracy.In 2008,King Wangchuck gave his power to, his son.Although the country still had a king,it held its first democratic elections that year. Bhutan had political parties and political candidates for the first time.Finally,Bhutan has connected to the rest of theworld through television and internet.Bhutan is a symbol for social progress.Many countries are now interested in Bhutan's GNH.Thesecountries are investigating their own ways to measure happiness.They want to create new policies that take care of their people,cultures,and land.Brazil may be the next country to use the principles of GNH.Brazilian leaders see the principles of GNI as a source of inspiration.Brazil is a large country with a diverse population.If happiness works as a measure of progress in Brazil,perhaps the rest of the world will follow.
[多选题]共用题干 第三篇On the Trial of the Honey BadgerOn a recent field trip to the Kalahari Desert,a team of researchers learnt a lot more about honey badgers(灌).The team employed a local wildlife expert,Kitso Khama,to help them locate and follow thebadgers across the desert. Their main aim was to study the badgers'movements and behaviour as discreetly (谨慎地)as possible,without frightening them away or causing them to change their natural behaviour. They also planned to trap a few and study them close up before releasing them.In view of the animal's reputation, this was something that even Khama was reluctant to do."The problem with honey badgers is that they are naturally curious animals,especially when they see something new,"he says."That,combined with their unpredictable nature,can be a dangerous mixture.If they sense you have food,for example,they won't be shy about coming right up to you for something to eat. They're actually quite sociable creatures around humans,but as soon as they feel they might be in danger, they can become extremely vicious(凶恶的). Fortunately this is rare , but it does happen."The research confirmed many things that were already known.As expected,honey badgers ate any crea-tures they could catch and kill.Even poisonous snakes,feared and avoided by most other animals,were notsafe from them.The researchers were surprised,however,by the animal's fondness for local melons,probably because of their high water content. Previously researchers thought that the animal got all of its liquid require- ments from its prey(猎物).The team also learnt that,contrary to previous research findings,the badgers oc- casionally formed loose family groups.They were also able to confirm certain results from previous research, including the fact that female badgers never socialised with each other.Following some of the male badgers was a challenge,since they can cover large distances in a short space of time.Some hunting territories cover more than 500 square kilometers.Although they seem happy to share these territories with other males,there are occasional fights over an important food source,and male badgers can be as aggressive towards each other as they are towards other species.As the badgers became accustomed to the presence of people,it gave the team the chance to get up closeto them without being the subject of the animals'curiosity一or their sudden aggression.The badgers'eating patterns,which had been disrupted,returned to normal.It also allowed the team to observe more closely some of the other creatures that form working associations with the honey badger,as these seemed to adopt the badgers'relaxed attitude when near humans. What did the team find out about honey badgers?
[单选题]Inquest told of hospital err A HOSPITAL err left a dying man on the wrong ward f two days asdeep vein thrombosis (DVT) ravaged his body, an inquest heard. Stephen MelvinNewbold suffered massive brain damage when a blood clot fmed in his veins.Now his families are considering legal action against Yk Hospital, sayingthat his death was “untimely unnecessary”. Mr Newbold, a 52-year-old maintenance wker, went to Yk Hospitalon November 3 complaining of a swollen right foot. He should have been sent toa surgical ward he would have been treated with1 Fragmin, a drug whichcounters the effects of DVT. However, hospital staff wrongly admitted him to2an thopedic ward, he stayed f two days, befe finally beingtransferred to the care of a consultant vascular surgeon. Twenty-four hourslater, on November 6, docts decided they would have to operate to remove hisleg below the knee. The operation went ahead on November 10, but two days later MrNewbold suffered a cardiac arrest. A scan revealed he had had a pulmonaryembolism, a condition related to DVT. Mr Newbold suffered brain damage diedin the hospital on November 16. Giving evidence, the surgeon said he could not explain why MrNewbold had been admitted to an thopedic ward it was not policy toadminister Fragmin. He did not know why his medical team had not given MrNewbold the drug later. Yk coner Donald Coverdale said, “From November 3until the day of the operation, no Fragmin was given to Mr Newbold. If he hadbeen admitted to a consultant vascular surgeon’s care from day one,it is clear that Fragmin would have been prescribed. Fragmin reduces the riskof DVT, but does not eliminate it. It is impossible to say whether Mr Newboldwould have suffered this DVT if he had received the Fragmin.” He recded averdict of death by misadventure. Kim Daniells, Mr Newbold’s family’s lawyer,said, “The family hope that the hospital will learn from the errs, that no other families will have to suffer in the future.” A spokeswoman f Yk Hospital’s NHS Trust said, “We wouldlike to extend our sincere sympathies to the family of Stephen Newbold duringthis difficult time.”   词汇: ward n.病房 vein n.血管 thrombosis n.血栓 clot n.凝块 maintenance n.维修,维护 Fragmin n.法安明(又名片段化蛋白) staff n.员工;职工 consultant n.顾问,咨询,会诊医师 surgeon n.心血管外科顾问 knee n.膝盖 embolism n.栓塞;栓塞形成 verdict n.裁决 misadventure n.灾难,不幸遭遇,意外事故 sympathy n.同情   注释: 1.be treated with...被用......药物进行治疗 2.be admitted to...被收容至,被移送至(本文中是“被送至病房”)   练习: 1.The patient was admitted with an injured foot.
[单选题]The Sahara Desert is the largest desert in the wld. It stretchesacross Africa from Senegal to Egypt. The Sahara Desert is an unfriendlyenvironment. During the day it's very hot, at night it’s sometimesvery cold. It is also difficult to find water in the Sahara. In 2006, Kevin Lin, Ray Zahab, Charlie Engle decided to dosomething very difficult. They made the decision to run across the SaharaDesert 4,300 miles (6,920km). It seemed impossible to do, but they wanted to try.The three men liked to test themselves, this would be a very big test. On the mning of November 2, Kevin, Ray, Charlie started theirtrip across the Sahara. Every mning they began running at 5:00. At11 a.m.they stopped rested until 5 p.m. Then they ran again until 9:30 in theevening. Each day they ran about 40 miles (64 km). Every day it was the samething. They got up ran. They listened to music on their iPods, they ran ran. Kevin, Ray, Charlie needed to eat a lot of food during theirtrip. Most people need about 2,000 calies of food each day. Kevin, Ray, Charlie needed between 6,000 9,000 calies every day. That's a lot offood! They also needed to drink a lot of water. The three men had some problems on their trip, many times theywanted to quit go home. It was often very hot (140°F/60°C) duringthe day, the heat made them sick. Their legs feet hurt. Sometimes itwas very windy, they couldn't see. One time they got lost. But they didn'tquit. After 111 days, Kevin, Ray; Charlie successfully finished their tripacross the Sahara Desert. They hugged each other put their hs in thewater of the Red Sea. Then they ran to a hotel to take a long shower.   词汇: stretch v. 延伸,伸展 calie n. 卡(路里),小卡,大卡 quit v. 停止,放   注释: 1. ... made the decision to run across ...:......决正跑步横跨......   练习:5. Sometimes they couldn't see the road because it was windy.
[单选题]The Sahara Desert is the largest desert in the wld. It stretchesacross Africa from Senegal to Egypt. The Sahara Desert is an unfriendlyenvironment. During the day it's very hot, at night it’s sometimesvery cold. It is also difficult to find water in the Sahara. In 2006, Kevin Lin, Ray Zahab, Charlie Engle decided to dosomething very difficult. They made the decision to run across the SaharaDesert 4,300 miles (6,920km). It seemed impossible to do, but they wanted to try.The three men liked to test themselves, this would be a very big test. On the mning of November 2, Kevin, Ray, Charlie started theirtrip across the Sahara. Every mning they began running at 5:00. At11 a.m.they stopped rested until 5 p.m. Then they ran again until 9:30 in theevening. Each day they ran about 40 miles (64 km). Every day it was the samething. They got up ran. They listened to music on their iPods, they ran ran. Kevin, Ray, Charlie needed to eat a lot of food during theirtrip. Most people need about 2,000 calies of food each day. Kevin, Ray, Charlie needed between 6,000 9,000 calies every day. That's a lot offood! They also needed to drink a lot of water. The three men had some problems on their trip, many times theywanted to quit go home. It was often very hot (140°F/60°C) duringthe day, the heat made them sick. Their legs feet hurt. Sometimes itwas very windy, they couldn't see. One time they got lost. But they didn'tquit. After 111 days, Kevin, Ray; Charlie successfully finished their tripacross the Sahara Desert. They hugged each other put their hs in thewater of the Red Sea. Then they ran to a hotel to take a long shower.   词汇: stretch v. 延伸,伸展 calie n. 卡(路里),小卡,大卡 quit v. 停止,放   注释: 1. ... made the decision to run across ...:......决正跑步横跨......   练习:6. Luckily, they never got lost.
[多选题]共用题干 New Understanding of Natural Silk's MysteriesNatural silk,as we all know,has a strength that man-made materials have long struggled to match.In a discovery that sounds more like an ancient Chinese proverb than a materials science breakthrough,MIT re- searchers have discovered that silk gets its strength from its weakness.Or,more specifically,its many weak- nesses. Silk gets its extraordinary durability and ductility(柔韧性)from an unusual arrangement of hydrogen bonds that are intrinsically very weak but that work together to create a strong,flexible structure.Most materials一especially the ones we engineer for strength一get their toughness from brittleness.As such,natural silks like those produced by spiders have long fascinated both biologists and engineers because of their light weight,ductility and high strength(pound for pound,silk is stronger than steel and far less brittle). But on its face,it doesn't seem that silks should be as strong as they are;molecularly,they are held together by hydrogen bonds , which are far weaker than the covalent(共价的)bonds found in other molecules.To get a better understanding of how silk manages to produce such strength through such weak bonds, the MIT team created a set of computer models that allowed them to observe the way silk behaves at the atomic level. They found that the arrangement of the tiny silk nanocrystals(纳米晶体)is such that the hydro- gen bonds are able to work cooperatively,reinforcing one another against external forces and failing slowlywhen they do fail,so as not to allow a sudden fracture to spread across a silk structure.The result is natural silks that can stretch and bend while retaining a high degree of strength.But while that's all well and good for spiders,bees and the like,this understanding of silk geometry could lead to new materials that are stronger and more ductile than those we can currently manufacture.Our best and strongest materials are generally expensive and difficult to produce(requiring high temperature treatments or energy-intensive processes).By looking to silk as a model,researchers could potentially devise new manufacturing methods that rely on inexpensive materials and weak bonds to create less rigid,more forgiving materials that are nonetheless stronger than anything currently on offer. And if you thought you were going to get out of this materials science story without hearing about carbon nanotubes(纳米碳管), think again. The MIT team is already in the lab looking into ways of synthesizing silk-like structures out of materials that are stronger than natural silk-like carbon nanotubes. Super-silks are on the horizon. The MIT team had tried different materials before they studied natural silk in their research.
[多选题]共用题干 Underground Coal FiresCoal burning deep underground in China,India and Indonesia is threatening the environment and human life , scientists have warned.These large-scale______(51)blazes(火焰)cause the ground temperature to heat up and kill surrounding vegetation,produce greenhouse gases and can______(52) ignite(点燃)forest fires , a group of scientists told the annual meeting of the American Association for theAdvancement of Science in Denver.The resulting______(53)of poisonous elements like mercury can also pollute local water sources and soils,they warned."Coal fires are a global disaster,"said Associate Professor Glenn Stracher of East Georgia College inSwainsboro,USA.But______(54)few people know about them.Coal can heat up on its own,and eventually catch fire and bum,if there is a continuous oxygen supply.The heat produced is not caused to______(55)and under the right combinations of sunlight and oxygen,can trigger spontaneous(自发的)catching fire and buming.This can occur underground , in coal stockpiles, abandoned mines or even as coal is transported.______(56)fires in China consume up to 200 million tons of coal per year,delegates were told.In______(57),the U.S.economy consumes about one billion tons of coal annually,said Stracher,______(58)analysis of the likely impact of coal fires has been accepted for publication in the International Journal of Coal Ecology.______(59)underway,coal fires can bum for decades,even centuries.In the process,they release large______(60)of greenhouse gases,poisonous fumes and black particles into the atmosphere.The members of the panel discussed the______(61)these fires may be having on global and regional climate change,and agreed that the underground nature of the fires makes them difficult to______(62).Ultimately,the remote sensing and other techniques should allow scientists to______(63)how much carbon dioxide these fires are emitting(释放).One suggested______(64)of containing the fires was presented by Gary Colaizzi,of the engineering firm Goodson,which has developed a heat-resistant grout(灌浆),which is designed to be pumped into the coal fire to______(65)the oxygen supply. _________60
[多选题]共用题干 第二篇Students Learn Better with Touchscreen DesksObserve the criticisms of nearly any major public education system in the world,and a few of the many complaints are more or less universal.Technology moves faster than the education system.Teachers must teach at the pace of the slowest student rather than the fastest. And一particularly in the United States一 school children as a group don't care much for,or excel(擅长)at,mathemnatics. So it's heartening to learn that a new kind of"classroom of the future"shows promise at easing some of these problems,starting with that fundamental piece of classroom furniture:the desk.A UK study involving roughly 400 students,mostly aged 8一10 years,and a new generation of multis-touch,multi-user,computerized desktop surfaces is showing that over the last three years the technology has appreciably boosted students'math skills compared with peers learning the same material via the con- ventional paper-and-pencil method.How?Through collaboration,mostly,as well as by giving teachers better tools by which to micromanage individual students who need some extra instruction while allowing the rest of the class to continue moving forward.Traditional instruction still shows respectable efficacy(效力)at increasing students'fluency in mathe- matics,essentially through memorization and practice一dull,repetitive practice.But the researchers have con-cluded that these new touchscreen desks boost both fluency and flexibility一the critical thinking skills that al- low students to solve complex problems not simply through knowing formulas and devices,but by being able to figure out what the real problem is and the most effective means of stripping it down and solving it.One reason for this,the researchers say,is the multi-touch aspect of the technology.Students working in the next-gen classroom can work together at the same tabletop,each of them contributing and engaging with the problem as part of a group.Known as SynergyNet,the software uses computer vision systems that see in the infrared(红外线的)spectrum to distinguish between different touches on different parts of the surface, allowing students to access and use tools on the screen,move objects and visual aids around on their desk- tops,and otherwise physically interact with the numbers and information on their screens.By using these screens collaboratively,the researchers say,the students are to some extent teaching themselves as those with a stronger grasp on difficult concepts pull other students forward along with them. Which of the following statements is NOT true of the public education system?
[多选题]共用题干 The Day a Language DiedWhen Carlos Westez died at the age of 76,a language died,too.Westez,more commonly known as Red Thunder Cloud,was the last speaker of the Native American language,Catawba.Anyone who wants to hear various songs of the Catawba can contact the Smithsonian Institution in Washington,D.C.,where, back in the 1940s,Red Thunder Cloud recorded a series of songs for future generations.______(46) They are all that is left of the Catawba language.The language that people used to speak is gone forever.We are all aware of the damage that modern industry can do to the world's ecology(生态).However, few people are aware of the impact that widely spoken languages have on other languages and ways of life.English has spread all over the world.Chinese,Spanish,Russian,and Hindi have become powerful languages,as well.______(47)When this happens,hundreds of languages that are spoken by only a few people die out.Scholars believe there are about 6 ,000 languages around the world,but more than half of them could die out within the next 100 years.There are many examples.Araki is a native language of the island of Vanuatu,located in the Pacific Ocean.It is spoken by only a few older adults,so like Catawba,Araki will soon disappear.Many languages of Ethiopia will have the same fate because each one has only a few speakers.______(48)In the Americas,100 languages,each of which has fewer than 300 speakers,also are dying out.Red Thunder Cloud was one of the first to recognize the threat of language death and to try to do something about it.He was not actually born into the Catawba tribe,and the language was not his mother tongue.______(49)The songs he sang for the Smithsonian Institution helped to make Native American music popular.Now he is gone,and the language is dead.What does it mean when a language disappears? When a plant or insect or animal species dies,it is easy to understand what we've lost and to appreciate what this means for the balance of the natural world.However,language is only a product of the mind.To be the last remaining speaker of a language,like RedThunder Cloud,must be a lonely destiny,almost as strange and terrible as being the last surviving member of a dying species.______(50) _______(48)
[多选题]共用题干 第三篇On the Trial of the Honey BadgerOn a recent field trip to the Kalahari Desert,a team of researchers learnt a lot more about honey badgers(灌).The team employed a local wildlife expert,Kitso Khama,to help them locate and follow thebadgers across the desert. Their main aim was to study the badgers'movements and behaviour as discreetly (谨慎地)as possible,without frightening them away or causing them to change their natural behaviour. They also planned to trap a few and study them close up before releasing them.In view of the animal's reputation, this was something that even Khama was reluctant to do."The problem with honey badgers is that they are naturally curious animals,especially when they see something new,"he says."That,combined with their unpredictable nature,can be a dangerous mixture.If they sense you have food,for example,they won't be shy about coming right up to you for something to eat. They're actually quite sociable creatures around humans,but as soon as they feel they might be in danger, they can become extremely vicious(凶恶的). Fortunately this is rare , but it does happen."The research confirmed many things that were already known.As expected,honey badgers ate any crea-tures they could catch and kill.Even poisonous snakes,feared and avoided by most other animals,were notsafe from them.The researchers were surprised,however,by the animal's fondness for local melons,probably because of their high water content. Previously researchers thought that the animal got all of its liquid require- ments from its prey(猎物).The team also learnt that,contrary to previous research findings,the badgers oc- casionally formed loose family groups.They were also able to confirm certain results from previous research, including the fact that female badgers never socialised with each other.Following some of the male badgers was a challenge,since they can cover large distances in a short space of time.Some hunting territories cover more than 500 square kilometers.Although they seem happy to share these territories with other males,there are occasional fights over an important food source,and male badgers can be as aggressive towards each other as they are towards other species.As the badgers became accustomed to the presence of people,it gave the team the chance to get up closeto them without being the subject of the animals'curiosity一or their sudden aggression.The badgers'eating patterns,which had been disrupted,returned to normal.It also allowed the team to observe more closely some of the other creatures that form working associations with the honey badger,as these seemed to adopt the badgers'relaxed attitude when near humans. Which of the following is a typical feature of male badgers?
[多选题]共用题干 Better Solar Energy Systems:More Heat,More LightSolar photovoltaic(光电的)thermal energy systems , or PVTs , generate both heat and electricity , but _________ (51)now they haven't been very good at the heat-generating part compared to a stand-alone solar thermal collector. That ' s because they operate at low temperatures to cool crystalline silicon(晶体硅)solar cells, _______(52)lets the silicon generate more electricity but isn't a very efficient way to gather heat.That's a problem of economics.Good solar hot-water systems can harvest much more energy than asolar一electric system at a substantially lower _________(53).And it's also a space problem:photovoltaiccells can_________(54)up all the space on the roof,leaving little room for thermal applications.In a pair of studies,Joshua Pearce,an associate professor of materials science and engineering,has de- vised a_________(55)in the form of a better PVT made with a different kind of silicon.Most solar panels are made with crystalline silicon,but you can also make solar cells out of amorphous(非晶形的)silicon , commonly known________( 56 ) thin-film silicon. They don ' t create as much elec-tricity,but they are lighter,flexible,and cheaper. And,because they________(57)much less silicon,they have a greener footprint._________(58),thin-film silicon solar cells are vulnerable to some bad一news physics in the form of the Staebler-Wronski effect."That means that their efficiency drops when you_________(59)them to light一pretty much the worst possible effect for a solar cell,"Pearce explains,which is one of the__________(60)thin-film solar panels make up only a small fraction of the market.However,Pearce and his team found a_______(61)to engineer around the Staebler-Wronski effect by incorporating thin-film silicon in a new________(62)of PVT. You don't have to cool down thin-film sili- con to make it work.In fact,Pearce's group discovered that by heating it to solar-thermal operating tempera- tures,near the boiling_________(63)of water,they could make thicker cells that largely_________(64) the Staebler-Wronski effect.When they applied the thin-film silicon directly to a solar thermal energy collector, they also found that by baking the cell once a day,they_________(65)the solar cell's electrical efficiency by over 10 percent. _________(54)
[多选题]共用题干 Climate Change:The Long Reach1.Earth is warming.Sea levels are rising.There's more carbon in the air,and Arctic ice is melting faster than at any time in recorded history.Scientists who study the environment to better gauge(评估) Earth's future climate now argue that these changes may not reverse for a very long time.2.People burn fossil fuels like coal and oil for energy.That burning releases carbon dioxide,a colorless gas.In the air,this gas traps heat at Earth's surface.And the more carbon dioxide released,the more the planet warms.If current consumption of fossil fuels doesn't slow,the long-term climate impacts could last thousands of years-and be more severe than scientists had been expecting.Climatologist RichardZeebe of the University of Hawaii at Manoa offers this conclusion in a new paper.3.Most climate-change studies look at what's going to happen in the next century or so.During that time, changes in the planet' s environment could nudge(推动)global warming even higher.For example, snow and ice reflect sunlight back into space.But as these melt,sunlight can now reach-and warm-the exposed ground.This extra heat raises the air temperature even more,causing even more snow to melt.This type of rapid exaggeration of impacts is called a"fast feedback".4.Zeebe says it's important to look at fast feedbacks.However,he adds,they're limited.From a climate change perspective,"This century is the most important time for the next few generations,"he told Science News."But the world is not ending in 2100."For this new study,Zeebe now focuses on"slow feedbacks".While fast feedback events unfold over decades or centuries,slow feedbacks can take thousands of years.Melting of continental ice sheets and the migration of plant life-as they relocate to more comfortable areas-are two examples of slow feedbacks.5.Zeebe gathered information from previously published studies investigating how such processes played out over thousands of years during past dramatic changes in climate.Then he came up with a forecast for the future that accounts for both slow and fast feedback processes.Climate forecasts that use only fast feedbacks predict a 4.5 degree Celsius(8.1 degree Fahrenheit)change by the year 3000.But slow feedbacks added another 1.5℃-for a 6℃ total increase,Zeebe reports.He also found that slow feedback events will cause global warming to persist for thousands of years after people run out of fossil fuels to burn. Paragraph 2______
[多选题]共用题干 Underground Coal FiresCoal burning deep underground in China,India and Indonesia is threatening the environment and human life , scientists have warned.These large-scale______(51)blazes(火焰)cause the ground temperature to heat up and kill surrounding vegetation,produce greenhouse gases and can______(52) ignite(点燃)forest fires , a group of scientists told the annual meeting of the American Association for theAdvancement of Science in Denver.The resulting______(53)of poisonous elements like mercury can also pollute local water sources and soils,they warned."Coal fires are a global disaster,"said Associate Professor Glenn Stracher of East Georgia College inSwainsboro,USA.But______(54)few people know about them.Coal can heat up on its own,and eventually catch fire and bum,if there is a continuous oxygen supply.The heat produced is not caused to______(55)and under the right combinations of sunlight and oxygen,can trigger spontaneous(自发的)catching fire and buming.This can occur underground , in coal stockpiles, abandoned mines or even as coal is transported.______(56)fires in China consume up to 200 million tons of coal per year,delegates were told.In______(57),the U.S.economy consumes about one billion tons of coal annually,said Stracher,______(58)analysis of the likely impact of coal fires has been accepted for publication in the International Journal of Coal Ecology.______(59)underway,coal fires can bum for decades,even centuries.In the process,they release large______(60)of greenhouse gases,poisonous fumes and black particles into the atmosphere.The members of the panel discussed the______(61)these fires may be having on global and regional climate change,and agreed that the underground nature of the fires makes them difficult to______(62).Ultimately,the remote sensing and other techniques should allow scientists to______(63)how much carbon dioxide these fires are emitting(释放).One suggested______(64)of containing the fires was presented by Gary Colaizzi,of the engineering firm Goodson,which has developed a heat-resistant grout(灌浆),which is designed to be pumped into the coal fire to______(65)the oxygen supply. _________61
[多选题]共用题干 Climate Change:The Long Reach1.Earth is warming.Sea levels are rising.There's more carbon in the air,and Arctic ice is melting faster than at any time in recorded history.Scientists who study the environment to better gauge(评估) Earth's future climate now argue that these changes may not reverse for a very long time.2.People burn fossil fuels like coal and oil for energy.That burning releases carbon dioxide,a colorless gas.In the air,this gas traps heat at Earth's surface.And the more carbon dioxide released,the more the planet warms.If current consumption of fossil fuels doesn't slow,the long-term climate impacts could last thousands of years-and be more severe than scientists had been expecting.Climatologist RichardZeebe of the University of Hawaii at Manoa offers this conclusion in a new paper.3.Most climate-change studies look at what's going to happen in the next century or so.During that time, changes in the planet' s environment could nudge(推动)global warming even higher.For example, snow and ice reflect sunlight back into space.But as these melt,sunlight can now reach-and warm-the exposed ground.This extra heat raises the air temperature even more,causing even more snow to melt.This type of rapid exaggeration of impacts is called a"fast feedback".4.Zeebe says it's important to look at fast feedbacks.However,he adds,they're limited.From a climate change perspective,"This century is the most important time for the next few generations,"he told Science News."But the world is not ending in 2100."For this new study,Zeebe now focuses on"slow feedbacks".While fast feedback events unfold over decades or centuries,slow feedbacks can take thousands of years.Melting of continental ice sheets and the migration of plant life-as they relocate to more comfortable areas-are two examples of slow feedbacks.5.Zeebe gathered information from previously published studies investigating how such processes played out over thousands of years during past dramatic changes in climate.Then he came up with a forecast for the future that accounts for both slow and fast feedback processes.Climate forecasts that use only fast feedbacks predict a 4.5 degree Celsius(8.1 degree Fahrenheit)change by the year 3000.But slow feedbacks added another 1.5℃-for a 6℃ total increase,Zeebe reports.He also found that slow feedback events will cause global warming to persist for thousands of years after people run out of fossil fuels to burn. Paragraph 3______
[多选题]共用题干 Solar Power Without Solar CellsA dramatic and surprising magnetic effect of light discovered by University of Michigan researchers could lead to solar power without traditional semiconductor-based solar cells.The researchers found a way to make an"optical________(51)",said Stephen Rand,a professor in the departments of Electrical Engineering and Computer Science,Physics and Applied Physics.Light has electric and magnetic_______(52).Until now,scientists thought the effects of the mag-netic field were so weak that they could be________(53).What Rand and his colleagues found is that at the right intensity,when light is traveling through a material that does not_________(54)electricity,the light field can generate magnetic effects that are 100 million times stronger than previously expected.Under these circumstances,the magnetic effects develop strength_________(55)to a strong electric effect."This could lead to a new kind of solar cell without semiconductors and without absorption to produce charge separation,"Rand said."In solar cells,the_________(56)goes into a matenal,gets absorbed and creates heat.Here,we expect to have a very low heat load.Instead of the light being absorbed,energy is stored in the magnetic moment.Intense magnetization can be induced by intense light and then it is ultimately capable of providing a capacitive power________(57)."What makes this possible is a previously unde- tected brand of"optical rectification",says William Fisher,a doctoral student in applied physics.In tradi- tional optical rectification,light's electric field causes a charge separation,or a pulling_________(58)of the positive and negative charges in a material.This sets up a voltage,similar to______(59)in a battery.Rand and Fisher found that under the right circumstances and in right types of materials,the light's magnetic field can also create optical rectification.The light must be shone through a________(60)that does not conduct electricity,such as glass.And it must be focused to an intensity of 10 million watts per square centimeter. Sunlight isn't this_______(61)on its own,but new materials are being sought that would work at lower intensities,Fisher said."In our most recent paper,we show that incoherent light like sunlight is theoretically almost _________(62)effective in producing charge separation as laser light is,"Fisher said.This new_________(63)could make solar power cheaper,the researchers say.They predict that with improved materials they could achieve 10 percent efficiency in converting solar power to usable energy.That's equivalent to today's commercial-grade solar cells."To manufacture modern solar cells,you have to do. _______(64)semiconductor processing,"Fisher said."All we would need are lenses to focus the light and a fiber to guide it.Glassworks for _________ (65).It's already made in bulk,and it doesn't require as much processing.Transparent ceramics might be even better." _________(54)
[多选题]共用题干 Musical Training Can Improve Communication SkillsAmerican scientists say musical training seems to improve communication skills and language retardation (延迟).They found that developing musical skill involves the______(51)process in the brain as learning how to speak.The scientists believe that could______(52)children with learning disabilities.Nina Krauss is a neurobiologist at Northwestern University in Illinois.She says musical training______(53)putting together different kinds of information,such as hearing music,looking at musical notes,touching an instrument and watching other musicians.This______(54)is not much different from learning how to speak.Both involve different senses.She further explains musical training and learning to______(55)each make us think about what we are doing.She says speech and music______(56)through a structure of the nervous system called the brain stem.The brain stem______(57)our ability to hear.Until recently,experts have thought the brain stem could not be developed or changed.______(58)Professor Krauss and her team found that musical training can improve a person's brain stem activity.The study involved individuals with different levels of musical______(59).They were asked to wear an electrical device that measures______(60)activity.The individuals wore the electrode while they watched a video of someone speaking and a person playing a musical instrument-the cello(大提琴).Professor Krauss says cellos have sound qualities similar______(61)some of the sounds that are impor-tant with speech.The study found that the more years of training people had,the more______(62)they were to the sound and rhythm of the music.Those who were involved in musical activities were the same people in whom the______(63)of sensory events was the strongest.It shows the importance of musical training to children with learning______(64).She says using music to improve listening skills could mean they______(65)sentences and understand facial expressions better. _________54
[多选题]共用题干 第三篇Eye-tracker Lets You Drag and Drop Files with a GlanceBored of using a mouse?Soon you'11 be able to change stuff on your computer screen-and then move it directly onto your smartphone or tablet(平板电脑)-with nothing more than a glance.A system called EyeDrop uses a head-mounted eye tracker that simultaneously records your field of view so it knows where you are looking on the screen.Gazing at an object-a photo,say-and then pressing a key,selects that object.It can then be moved from the screen to a tablet or smartphone just by glancing at the second device,as long as the two are connected wirelessly."The beauty of using gaze to support this is that our eyes naturally focus on content that we want toacquire,"says Jayson Turner,who developed the system with colleagues at Lancaster University,UK.Turner believes EyeDrop would be useful to transfer an interactive map or contact information from a public display to your smartphone or tablet for sharing photos.A button needs to be used to select the object you are looking at otherwise you end up with the"Midas touch"(点石成金)effect, whereby everything you look at gets selected by your gaze, says Turner."Imagine if your mouse clicked on everything it pointed at,"he says.Christian Holz,a researcher in human-computer interaction at Yahoo Labs in Sunnyvale,California, says the system is a nice take on getting round this fundamental problem of using gaze-tracking to interact."EyeDrop solves this in a slick(灵巧的)way by combining it with input on the touch devices we carry with us most of the time anyway and using touch input as a clutching mechanism,"he says."This now allows users to seamlessly(无缝地)interact across devices far and close in a very natural manner."While current eye-trackers are rather bulky,mainstream consumer devices are not too far away.Swedish firm Tobii is developing gaze-tracking technology that can be installed in laptops and tablets and is expected to be available to buy next year.And the Google Glass headset is expected to include eye-tracking in the future.Turner says he has also looked at how content can be cut and pasted or drag-and-dropped using a mix of gaze and taps on a touchscreen.The system was presented at the Conference on Mobile and Ubiquitous Multimedia in Sweden,last week. The eye-tracker technology enables us to______.
[多选题]共用题干 The Mysteries of NazcaIn the desert of Peru,300 kilometers from Lima,one of the most unusual artworks in the world has mystified(迷惑)people for decades._________ (46 ) But from high above,these marks are huge images of birds,fish,seashells,all beautifully carved into the earth.The Nazca lines are so difficult to see from the ground that they weren't discovered until the 1930s, when pilots spotted them while flying over the area. In all,there are about 70 different human and animal figures on the plain,along with 900 triangles,circles,and lines.Researchers have figured out that the lines are at least 1,500 years old,but their purpose is still a mystery.__________(47)However,it would probably be very tricky to land a spaceship in the middle ofpictures of dogs and monkeys.In the 1940s,an American explorer named Paul Kosok suggested that the drawings are a chronicle(记 录)of the movement of the stars and planets._________(48)Later,an astronomer tested his theory with a computer,but he couldn' t find any relation between the lines and movements in space.Another explanation is that the lines may have been made for religious reasons.British researcher Tony Morrison investigated the customs of people in the Andes Mountain and learned that they sometimes pray by the side of the road.It's possible that in the past,the lines of Nazca were created for a similar purpose. _________(49)But the local people have never constructed anything this big.Recently,two other scientists,David Johnson and Steve Mabee,have speculated that lines could have been related to water. Nazca is one of the driest places in the world and receives only 2cm of rain every year. While Johnson was searching for ancient water sources in the area,he noticed that some waterways built by ancient people were connected with the lines.Johnson believes that the Nazca lines are a giant map of the underground water in the area._________(50) _________(47)
[多选题]共用题干 Black Holes1 Black holes can be best described as a sort of vacuum,sucking up everything in space.Scientists have discovered that black holes come from an explosion of huge stars.Stars that are near death can no longer burn due to loss of fuel , and because its temperature can no longer control the gravitational(重力的)force,hydrogen ends up putting pressure onto the star's surface until it suddenly explodes then collapses.2 Black holes come from stars ihat are made of hydrogen,other gases and a few metals.When these explode it can turn into a stellar-mass(恒星质量) black hole , which can only occur if the star is large enough (should be bigger than the sun)for the explosion to break it into pieces,and the gravity starts to compact every piece into the tiniest particle.Try to see and compare:if a star that's ten times the size of the sun ends up being a black hole that's no longer than 70 kilometers,then the Earth would become a black hole that'S only a fraction of an inch!3 Objects that get sucked in a black hole will always remain there,never to break free.i1it remember that black holes can only gobble up(吞噬)objects within a specific distance to it.It's possible for a large star near the sun to become a black hole,but the sun will continue to stay in place.Orbits(轨道)do not change because the newly formed black hole contains exactly the same amount of mass as when it was a star, only this time its mass is totally contracted that it can end up as no bigger than a state.4 Sofar,astronomers have figured out that black holes exist because of Albert Einstcin's theory of relativity.In the end,through numerous studies,they have discovered that black holes truly exist.Since black holes trap light and do not give off light,it is nearly impossible to detect black holes via a telescope.But astronomers continue to study galaxies(银河系), space and the solar system to understand how black holes might evolve.It is possible that black holes can exist for millions of years,and later contribute to a bigger process in galaxies,which can eventually lead to creation of new entities(实体).Scientists also credit black holes as helpful in learning how galaxies began to form. Black holes are formed after_________.