理工A

考试试题

[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. After fossil fuels are used up,global warming will continue for______.
[多选题]共用题干 Study Helps Predict Big Mediterranean Quake1.Scientists have found evidence that an overlooked fault in the eastern Mediterranean is likely to produce an earthquake and tsunami every 800 years as powerful as the one that destroyed Alexandria in AD 365.2.Using radiocarbon dating techniques,simulations and computer models,the researchers recreated the ancient disaster in order to identify the responsible fault."We are saying there is probably a repeat time of 800 years for this kind of earthquake,"said Ms Beth Shaw,an earthquake scientist at the University of Cambridge,who led the study. Scientists study past earthquakes in order to deter-mine the future possibility of similar large shocks.3.Identifying the fault for the AD 365 earthquake and tsunami is important for the tens of millions of people in the region,Ms.Shaw said.The fault close to the southwest coast of Crete last produced a big enough quake to generate a tsunami about 1300,which means the next powerful one could come in the next 100 years,she added in a telephone interview.4.Ms.Shaw and her colleagues calculate the likely intervals by measuring the motion of either side of the fault to find how often such large earthquakes would have to occur to account for that level of motion,she said.Their computer model suggested an 8 magnitude quake on the fault would pro-duce a tsunami that floods the coastal regions of Alexandria and North Africa,the southern coast of Greece and Sicily all the way up the Adriati to Dubrovnik.This would be similar to the ancient quake in AD 365 that caused widespread destruction in much of Greece and unleashed a tsunami that flooded Alexandria and the Nile Delta likely killing tens of thousands of people,she said. Ms.Shaw has her colleagues help her in the study of earthquake prediction.
[多选题]共用题干 InflationBusiness and government leaders also consider the inflation rate to be an important general indicator. Inflation is a period of increased spending that causes rapid rises in prices._______(51)your money buys fewer goods so that you get_______(52)for the same amount of money as before,inflation is the problem. There is a general rise_______(53)the price of goods and services.Your money buys less.Sometimes people describe inflation as a time when"a dollar is not worth a dollar anymore".Inflation is a problem for all consumers.People who live on a fixed income are hurt the _______(54).Retired people,for instance,cannot count on an increase in income as prices rise. Elderly people who do not work face serious problems in stretching their incomes to_______(55) their needs in time of inflation.Retirement income_______(56)any fixed income usually does not rise as fast as prices.Many retired people must cut their spending to_______(57)rising prices.In many cases they must stop_______(58)some necessary items,such as food and clothing. Even _______(59)working people whose incomes are going up,inflation can be a problem. The_______(60)of living goes up,too. People who work must have even more money to keep up their standard of living. Just buying the things they need costs more.When incomes do not keep _______(61)with rising prices,the standard of living goes down.People may be earning the same amount of money,but they are not living as well because they are not able to buy as many goods and services.Government units gather information about prices in our economy and publish it as price indexes _______(62)the rate of change can be determined.A price index measures changes in prices using the price for a_______(63)year as the base.The base price is set at 100,and the other prices are reported as a_______(64)of the base price.A price index makes_______(65)possible to compare current prices of typical consumer goods,for example,with prices of the same goods in previous years. _________(61)
[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." _________(55)
[多选题]共用题干 The Differences Among Various Types of AdoptionIn the US,there is a difference between public and private adoption.Public adoption typically involves taking _________ (51) foster(收养的)children and then adopting them after several months.It's significantly less expensive than private or international adoption,but more often than not_______(52)adopting children who are older than 5 or who have_______(53)needs.Private adoptions offer a better chance of adopting newborns,and increasingly,birth parents _______(54)the adoptive parents themselves.That's not a bad idea on its face,as it gives biological parents_______ (55)say in whom they will relinquish(放弃)their children. But this effectively puts_______(56)parents in the position of advertising themselves to birth parents in newspapers and online,_______(57)many couples feel uncomfortable with.Most states allow birth parents to reclaim their children_______(58)the children have been placed with adoptive families,for time periods ranging from a few days in some states to several months in others.Critics of international adoption say this rarely happens.They are only_______ (59)right:it's true that American birth parents don't usually reclaim their children once they've been placed with their adoptive families,but they can and do_______(60)their minds before the papers are signed.International adoption is more expensive than any form of domestic adoption,but in many ways, it is also more straightforward.The_______(61)of a birth parent calling the adoption_______ (62)are effectively zero and while costs are high,they're also determined at the_______(63) and tend not to change as the_______(64)wears on.Couples seeking to adopt should consider all_______(65)and get a range of perspectives before deciding which method is best for them. _________(65)
[多选题]共用题干 The Differences Among Various Types of AdoptionIn the US,there is a difference between public and private adoption.Public adoption typically involves taking _________ (51) foster(收养的)children and then adopting them after several months.It's significantly less expensive than private or international adoption,but more often than not_______(52)adopting children who are older than 5 or who have_______(53)needs.Private adoptions offer a better chance of adopting newborns,and increasingly,birth parents _______(54)the adoptive parents themselves.That's not a bad idea on its face,as it gives biological parents_______ (55)say in whom they will relinquish(放弃)their children. But this effectively puts_______(56)parents in the position of advertising themselves to birth parents in newspapers and online,_______(57)many couples feel uncomfortable with.Most states allow birth parents to reclaim their children_______(58)the children have been placed with adoptive families,for time periods ranging from a few days in some states to several months in others.Critics of international adoption say this rarely happens.They are only_______ (59)right:it's true that American birth parents don't usually reclaim their children once they've been placed with their adoptive families,but they can and do_______(60)their minds before the papers are signed.International adoption is more expensive than any form of domestic adoption,but in many ways, it is also more straightforward.The_______(61)of a birth parent calling the adoption_______ (62)are effectively zero and while costs are high,they're also determined at the_______(63) and tend not to change as the_______(64)wears on.Couples seeking to adopt should consider all_______(65)and get a range of perspectives before deciding which method is best for them. _________(62)
[多选题]共用题干 What's Killing the BatsFirst it was bees.Now it is bats.Biologists in America are working hard to discover the cause of the mysterious deaths of tens of thousands of bats in the northeastern part of the country.Most of the bats affected are the common little brown bats(Myotis lucifugus,)but other species, such as the long-eared bat,the small-footed bat,the eastern pipistrelle,and the Indiana bat have also been affected. In some caves,more than 90 percent of the bat populations have died.One possibility is disease. A white fungus(真菌)known as fusarium has been found on the noses of both living and dead bats.However,scientists don't know if the fungus is the primary cause of death,a secondary cause of death,or not a cause at all,but the result of some other conditions.Another possible cause is a lack of food.For example,bats typically eat a large number of moths(蛾),and in some states such as New York,the number of moths has been declining in recent years. if bats can't eat enough food,they starve to death.Still other scientists believe that global warming is to blame.Warmer temperatures in recent years have been waking up hibernating(冬眠)bats earlier than usual. If bats break their hiberna- lion at the wrong time,they might not find their expected food sources. The weather might also turn cold again and weaken or kill the bats.Scientists might not agree on the causes of the bat die-off, but they do agree on the conse- quences. Bats are an important predator of mosquitoes:a single brown bat can eat 1,000 or more insects in an hour. They also eat beetles and other insects that damage plant crops.If there aren't enough bats,damage will be great from the insects they eat. While bats live a long time for their size-the little brown bat can live for more than 30 years-a female bat has only one baby per year,so bat populations grow slowly. Many bat species in the United States are already protected or endangered.How can you help?Do not disturb sleeping or nesting bats.If you discover bats that seem to be sick or that are dead,contact your local Fish& Wildlife Department with the details.However, be careful not to touch the animals. What does the first sentence in Paragraph 1 mean?
[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 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." Dr.Alpa Patel was______.
[多选题]共用题干 Computer Plug-in1.Life on the Internet can be enriched if you don't restrict yourself to just written words and still pictures.Even if you are a newcomer to the Internet world,you've probably heard about multi-media on-line一listening to radio,watching animations and videos,even playing in three-dimensional space.Sound and movement make information come alive.2.In order to experience that,some special pieces of software called plug-ins are necessary. The term"plug-in"refers to a small,add-on piece of software which extends the capabilities of your web browser,like Netscape Navigator or Microsoft Explorer,turning your computer into a radio or TV.3.When you open a web page with a file requiring a plug-in which you don't have.you will usually receive a message asking if you want to get it by downloading it and installing it into your computer. Most of the time,the installation will be automatic.4.Occasionally,you come across a downloaded file which needs to be decompressed or unzipped before installation.Once installed,plug-ins run automatically,without you having to do anything.5.Many multimedia controls still need to be obtained from the developer but are installed automatically.6.Shockwave is a typical example of it. All you need to do is go to the Macromedia site and click on the link to install the ActiveX control.The rest happens automatically.The next time you go to a"Shocked"website,the Shockwave control loads and plays the movie.7.Most plug-ins and controls can be downloaded for free on the Internet,although not all will work with every system.Some of them,for instance,only work with Windows 95. Many multimedia controls still need to be_______from the developer but are installed automatically.
[多选题]共用题干 Study Helps Predict Big Mediterranean Quake1.Scientists have found evidence that an overlooked fault in the eastern Mediterranean is likely to produce an earthquake and tsunami every 800 years as powerful as the one that destroyed Alexandria in AD 365.2.Using radiocarbon dating techniques,simulations and computer models,the researchers recreated the ancient disaster in order to identify the responsible fault."We are saying there is probably a repeat time of 800 years for this kind of earthquake,"said Ms Beth Shaw,an earthquake scientist at the University of Cambridge,who led the study. Scientists study past earthquakes in order to deter-mine the future possibility of similar large shocks.3.Identifying the fault for the AD 365 earthquake and tsunami is important for the tens of millions of people in the region,Ms.Shaw said.The fault close to the southwest coast of Crete last produced a big enough quake to generate a tsunami about 1300,which means the next powerful one could come in the next 100 years,she added in a telephone interview.4.Ms.Shaw and her colleagues calculate the likely intervals by measuring the motion of either side of the fault to find how often such large earthquakes would have to occur to account for that level of motion,she said.Their computer model suggested an 8 magnitude quake on the fault would pro-duce a tsunami that floods the coastal regions of Alexandria and North Africa,the southern coast of Greece and Sicily all the way up the Adriati to Dubrovnik.This would be similar to the ancient quake in AD 365 that caused widespread destruction in much of Greece and unleashed a tsunami that flooded Alexandria and the Nile Delta likely killing tens of thousands of people,she said. Scientists predict that the next powerful earthquake in the eastern Mediterranean may take place some time before 2100.
[多选题]共用题干 Virtual DriverDriving involves sharp eyes and keen ears,analyzing with a brain,and coordination between hands,feet and brain.A man has sharp eyes and keen ears,analyzes through his brain,and maintains coordination between his hands and brains.He can control a fast-moving car with different parts of his body._______(46)Apparently there isn't anyone in the driver's cab,but there is in fact a virtual driver. This virtual driver has eyes,brains,hands and feet too.The minicameras on each side of the car are its eyes and are responsible for observing the road conditions ahead of it as well as the traffic to its left and right.If you open the boot,you can see the most important part of the automatic driving system:a built-in computer._______(47)The brain is responsible for calculating the speeds objects surrounding the car are moving at,analyzing their position on the road, choosing the right path,and giving orders to the wheel and the control system.In comparison with the human brain,the virtual driver's best advantage is that it reacts quickly. _______(48)However,it takes the world's best racecar driver at least one second to react,and this doesn't include the time he needs to take action.With its rapid reaction and accurate control,the virtual driver can reduce the accident rate on expressways considerably.In this case,is it possible for us to let it have the wheel at any time and in any place?_______(49)With its limited ability to recognize things,the car can now only travel on expressways.The intelligent car determines its direction by the clear lines that mark the lanes clearly and recognizes vehicles according to their regular shapes._______(50)This being the case,people still have high hopes about driverless cars,and think highly intelligent cars are what the cars of the future should be like. ________(46)
[多选题]共用题干 Historic Route 66:The Story of America's"Mother Road"1. The idea for Route 66 started in Oklahoma.Citizens there wanted to link their state with states to the east and west.By the l920s,federal officials wanted to connect state roads to provide a shorter,faster way across the country.So a plan was developed to connect existing state roads into one long national highway.2. United States Highway 66 was established on November 11,1926.It was one of the first federal highways .It crossed eight states.It was 3,800 kilometers long.Route 66 became the most famous road in America.It passed through the center of many cities and towns. It crossed deserts, mountains,valleys and rivers.3. In the 1930s,people suffered through the Great Depression.In Oklahoma,many poor families lost their farms because of dust storms.So they traveled west to California on Route 66 in search of a better life.In 1939,John Steinbeck wrote about these families in"The Grapes of Wrath."4. In his book,Steinbeck wrote:"66-the long concrete path across the country,waving gently up and down on the map,over the red lands and the gray lands,twisting up into the mountains, crossing the Divide and down into the bright and terrible desert,and across the desert to the mountains again,and into the rich California valleys."Steinbeck wrote:"66 is the path of a people in flight,refugees from dust and shrinking land.66 is the mother road,the road of flight."5. In 1946,the songwriter Bobby Troup and his wife drove across the country to Los Angeles.He wrote a song about traveling on Route 66 .The song told people they could have fun,could get their kicks,on that drive.In Los Angeles,Bobby Troup took the song to Nat King Cole,who recorded it. It became a huge hit.6. In the 1950s,holiday travel brought more and more families out West to explore.Route 66 represented the spirit of movement and excitement.In the 1960s,Americans watched a popular television series called"Route 66."It was the story of two young men driving across the country.The show was filmed in cities and towns across America.Yet only a few shows were filmed on the real Route 66.7. In real life,people were getting fewer and fewer kicks on Route 66.By 1962,parts of the road were closed because they were in poor condition.The federal government was building bigger highways .Cars and trucks could travel at higher speeds. People started driving on these new interstate highways instead of the old Route 66 .Finally,in 1985,Route 66 was officially removed from the national highway system.People have formed groups to save parts of the old 66 and many of the interesting places to eat,stay and see along the way. During the Great Depression,many poor families in Oklahoma lost their farms because of______.
[多选题]共用题干 Experience the World in 3D Game Ever wondered how your cat or dog sees the world?Now you can look through their eyes with the first 3 D game that recreates the vision of different species based on scientific evidence. The online simulation,created by the French 3 D design company Dassault Systemes,with the guidance of veterinary ophthalmologist(眼科专家)Didier Schmidt-Morand , mimics(模仿)the vision of five animals-cats,dogs,rats,hawks and bees-as a player steers them through Place in Paris. Due to differences in field of view,colour perception and night vision,for example,sight can be drastically different from species to species."In terms of performance,eyes are as variable as different models of cars,"says Schmidt-Morand. The game was created by using existing virtual models of the square then applying effects based on descriptions of each animal's vision.Dassault's 3 D software allows a scene to be modified by adding blur or changing the colours,angle of vision and depth of field. Although it was easy to recreate vision inferior to that of humans-cats and dogs,for example,have trouble distinguishing shades of red-replicating features that we are unable to see was a challenge.Hawks have more detailed vision than ours,whereas dogs are better at seeing movement and have a wider field of view."We used virtual cameras to precisely simulate larger viewing angles but the result made people nauseous(令人作呕的),"says Schmidt-Morand."So we tweaked(微调)the model to give a sense of the wider view without sticking to reality." The rat's view also departs from reality:because they are near-sighted,everything more than 15 centimetres away is a blur,so they typically move close to walls to help them navigate."A rat would never throw itself into the middle of an open area,"says Schmidt-Morand.The simulation for this animal is supplemented with a map in the top right corner to help determine the rat's position:because of their limited eyesight,most landmarks are obscured. The game is intended as an educational resource and players can discuss their experience with others through community features on the website.If there is interest from schools and zoos,the team hopes to recreate the vision of more animals. The game developed by Dassault Systemes is the first 3D game recreating the vision of different species.
[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 size of Europa is a bit larger than that of Earth's moon.
[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 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)
[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. _________(58)
[多选题]共用题干 Few Facts about Singapore1. Singapore is an independent city state in southeastern Asia,consisting of one major island-the Singapore Island-and more than 50 small islands,located off the southern tip of Malay.The city of Singapore,the capital of the country,is at the southeastern end of the Singapore Island;it is one of the most important port cities and commercial centers of Southeast Asia. The total area of the re- public is 640 sp.km.2. Low lying Singapore Island has no outstanding relief(轮廓鲜明的)features. A central area of hills rises to the maximum height of 176 m.The country has a wet tropical climate,with an average annual temperature of 27 .20℃.The average annual rainfall is 2,413 mm;the wettest months are November through January.3. Singapore is governed under a constitution of 1959.A president,elected to a four-year term is head of state,and a prime minister is head of government. The president used to be selected by Parliament ,but by a 1991 constitutional amendment(修正案),the president is now elected direct-ly by the people.The Parliament is the law making body with its 81 members popularly elected.4. In the late 1980s the country had some 290 primary schools with 278,300 pupils and 160 secondary schools with 200,200 students.The main institutions of higher education are the NationalUniversity of Singapore,several technical colleges,and a teachers college.5. Singapore has one of the highest standards of living of any country in Asia. In the late 1980s the gross domestic product was estimated at$23 .7 billion,or$8,870 per person.The fishing industry is centered on the port of southwestern Singapore Island.Industry has grown rapidly since the 1 960s , and Singapore now produces a diversity(多样化的)of goods , including chemicals ,electronic items,clothing,and processed foods,etc.Shipbuilding and petroleum refining are also important. Compared with people in other Asian countries,the Singaporeans______.
[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) _________(46)
[多选题]共用题干 Sharks Perform a Service for Earth's WatersIt is hard to get people to think of sharks as anything but a deadly enemy.They are thought to ______(51)people frequently .But these fish perform a______(52)service for earth's waters and for human beings .Yet business and sport fishing are threatening their______(53).Some sharks are at______(54)of disappearing from earth.Warm weather may influence both fish and shark activity.Many fish swim near coastal areas ______(55)their warm waters. Experts say sharks may follow the fish into the same areas, ______(56)people also swim.In fact,most sharks do not purposely charge at or bite humans.They are thought to mistake a person______(57)a sea animal,such as a seal or sea lion.That is why people should not swim in the ocean when the sun goes down or comes up .Those are the ______(58)when sharks are looking for food.Experts also say that bright colors and shiny jewelry may cause sharks to attack.A shark has an extremely good sense of smell.It can find small amounts of substances in water,such as blood,body liquids and______(59)produced by animals.These powerful ______(60)help sharks find their food.Sharks eat fish,any______(61)sharks,and plants that live in the ocean.Medical researchers want to learn more about the shark's body defense and immune systems ______(62)disease.Researchers know that sharks______(63)quickly from injuries.They study the shark in hopes of finding a way to fight human disease.Sharks are important for the world's______(64).They eat injured and diseased fish. Their hunting activities mean that the numbers of other fish in ocean waters do not become too ______(65).This protects the plants and other forms of life that exist in the oceans. 59._________
[多选题]共用题干 第二篇Sleep Lets Brain File MemoriesTo sleep.Perchance to file?Findings published online this week by the proceedings of the National Academy of Sciences further support the theory that the brain organizes and stows memories formed during the day while the rest of the body is catching zzz's.Gyorgy Buzsaki of Rutgers University and his colleagues analyzed the brain waves of sleeping rats and mice. Specifically,they examined the electrical activity emanating(散发)from the somatosensory(耳、目、口等以外的)neocortex(新大脑皮层)(an area that processes sensory information) and the hippocampus(海马),which is a center for learning and memory. The scientists found that oscillations in brain waves from the two regions appear to be intertwined.So-called sleep spindles (bursts of activity from the neocortex)were followed tens of milliseconds later by beats in the hippocampus known as ripples.The team posits that this interplay between the two brain regions is a key step in memory consolidation.A second study,also published online this week by the proceedings of the National Academy of Sciences,links age-associated memory decline to high glucose levels.Previous research had shown that individuals with diabetes(糖尿病,多尿症)suffer from increased memory problems.In the new work,Antonio Convit of New York University School of Medicine and his collaborators studied 30 people whose average age was 69 to investigate whether sugar levels,which tend to increase with age,affect memory in healthy people as well.The scientists administered recall tests, brain scans(细看,审视,浏览,扫描)and glucose tolerance tests, which measure how quickly sugar is absorbed from the blood by the body's tissues.Subjects with the poorest memory recollection,the team discovered,also displayed the poorest glucose tolerance.In addition,their brain scans showed more hippocampus shrinkage than those of subjects better able to absorb blood sugar." Our study suggests that this impairment(损害、损伤)may contribute to the memory deficits (赤字、不足额)that occur as people age."Convit says."And it raises the intriguing possibility that improving glucose tolerance could reverse some age-associated problems in cognition."Exercise and weight control can help keep glucose levels in check(阻止、制止),so there may be one more reason to go to the gym. What is the result of the experiment with rats and mice carried out at Rutgers University?
[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. Among the elements of noble gases helium is the__________.
[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. A country shows its progress with GNP by_________.
[多选题]共用题干 Natural Gas1 Natural gas is produced from reservoirs deep beneath the earth's surface. It is a fossil fuel(矿物燃 料),meaning that it is derived from orgaiiic material buried in the earth millions of years ago.The main corn- ponent of natural gas is methane(甲烷).2 The popularity and use of clean natural gas have increased dramatically over the past 50 years as pipeline infrastructure(基础设施)has been installed to deliver it conveniently and economically to millions of residential,commercial and industrial customers worldwide.Today,natural gas service is available in all 50 states in the U.S.,and is the leading energy choice for fueling American homes and industries.More than 65 million American homes use natural gas.In fact,natural gas is the most economical source for home energyneeds,costing one-third as much as electricity.In addition to heating homes,much of the gas used in the United States is used as a raw material to manufacture a wide variety of products,from paint,to fibers for clothing,to plastics for healthcare,computing and furnishings.Natural gas is also used in a significant number of new electricity-generating power plants.3 Natural gas is one of the safest and cleanest fuels available. It emits(发出)less pollution than other fossil fuel sources. When natural gas is burned , it produces mostly carbon dioxide(二氧化碳)and water va- por一the same substances emitted when humans breathe.Compared with some other fossil fuels,natural gas emits the least amount of carbon dioxide into the air when combusted(燃烧)一making natural gas the clea-nest burning fossil fuel of all.4 The United States consumes about one一third of the world's natural gas output,making it the largest gas-consuming region in the world.The U.S.Department of Energy Information Administration forecasts that natural gas demand will grow by more than 50 percent by 2025.5 There are huge reserves of natural gas beneath the earth's surface.The largest reserves of natural gas can be found in Russia , West and North Africa and the Middle East. LNG(液化天然气)has been pro- duced domestically and imported in the United States for more than four decades.Today,the leading import- ers of LNG are Japan,Korea,France and Spain. Paragraph 3__________
[多选题]共用题干 第一篇The News Industry in USWhy do so many Americans distrust what they read in their newspapers?The American Society of Newspaper Editors is trying to answer this painful question.The organization is deep into a long self-analysis known as the journalism credibility project.Sad to say,this project has turned out to be mostly low-level findings about factual errors and spelling and grammar mistakes,combined with lots of head-scratching puzzlement about what in the world those readers really want.But the sources of distrust go way deeper. Most journalists learn to see the world through a set of standard templates(patterns)into which they plug each day's events.In other words,there is a conventional story line in the newsroom culture that provides a backbone and a ready-made narrative structure for otherwise confusing news.There exists a social and cultural disconnect between journalists and their readers,which helps explain why the"standard templates"of the newsroom seem alien to many readers.In a recent survey,questionnaires were sent to reporters in five middle-size cities around the country,plus one large metropolitan area. Then residents in these communities were phoned at random and asked the same questions.Replies show that compared with other Americans,journalists are more likely to live in upscale neighborhoods,have maids,own Mercedeses,and trade stocks,and they're less likely to go to church, do volunteer work,or put down roots in a community.Reporters tend to be part of a broadly social and cultural elite,so their work tends to reflect the conventional values of this elite. The astonishing distrust of the news media isn't rooted in inaccuracy or poor reportorial skills but in the daily clash of world views between reporters and their readers.This is an explosive situation for any industry,particularly a declining one.Here is a troubled business that keeps hiring employees whose attitudes vastly annoy the customers.Then it sponsors lots of symposiums and a credibility project dedicated to wondering why customers are annoyed and fleeing in large numbers.But it never seems to get around to noticing the cultural and class biases that so many former buyers are complaining about. If it did,it would open up its diversity program, now focused narrowly on race and gender,and look for reporters who differ broadly by outlook, values,education,and class. The results of the journalism credibility project turned out to be_______.
[多选题]共用题干 To Survive or to Vanish1.Over 3.6 billion years ago,the first creature was born in the world.Since then,the earth started its era with life.The history of life on earth has been a history of interaction between living things and their surroundings.To a large extent,the physical form and the habits of the earth's vegetation and its animal life have been molded by the environment. Considering the whole span of earthly time,the opposite effect,in which life actually modifies its surroundings,has been relatively slight. Only in the present century has one species一man acquired significant power to alter the nature of his world.2.During the past 25 years,this power has not only become increasingly great but it has changed in character. The most alarming of all man's assaults upon the environment is the contamination of air,earth,rivers,and sea with dangerous and even lethal materials. This pollution is for the most part irrecoverable.In this now universal contamination of the environment,chemicals are the sinister partners of radiation in changing the very nature of the world the very nature of its life. Chemicals sprayed on croplands or forests or gardens lie long in soil,entering into living organisms, passing from one to another in a chain of poisoning and death.Or they pass mysteriously by underground streams until they emerge and combine into new forms that kill vegetation,sicken cattle,and work unknown harm on those who drink from once pure wells."Man can hardly even recognize the devils of his own creation,"as a scientist has said.3.Hundreds of millions of years have passed before the globe produced the life that now inhabits the earth.Given time not in years but in millennia life adjusts,and a balance has been reached.But in the modern world there is no time.4.The quick steps of change follows the impetuous pace of man rather than the deliberate pace of nature.Radiation is now the unnatural creation of man's tampering with the atom.The chemicals are the synthetic creations of man's inventive mind,having no counterparts in nature.5.To survive these chemicals would require not merely the years of one man's life but the life of generations.And even this,were it by some miracle possible,would be futile,for the new chemicals come from our laboratories in an endless stream;almost five hundred annually find their way into actual use in the United States alone.Among them are many that are used in man's war against nature.Since the mid l940's over 200 basic chemicals have been created for use in killing insects,weeds,and other organisms described as"pests".6.It is not my contention that chemical insecticides must never he used.I do contend that we have put poisonous and biologically potent chemicals indiscriminately into the hands of persons largely or wholly ignorant of their potentials for harm. We have subjected enormous numbers of people to contact with these poisons,without their consent and often without their knowledge.I contend,furthermore,that we have allowed these chemicals to be used with little or no advance investigation of their effect on soil,water,wildlife,and man himself. Future generations are unlikely to forgive our lack of concern for the integrity of the natural world that supports all life. Human's pollution on nature is for the most part_______.
[多选题]共用题干 “Salty” Rice Plant Boosts HarvestsBritish scientists are breeding a new generation of rice plants that will be able to grow in soil containing salt water. Their work may enable abandoned farms to become productive once more.Tim Flowers and Tony Yeo,from Sussex University's School of Biological Sciences,have spent several years researching how crops,such as rice,could be made to grow in water that has become salty.The pair have recently begun a three-year programme,funded by the Biotechnology and Biological Sciences Research Council,to establish which genes enable some plants to survive salty conditions. The aim is to breed this capability into crops,starting with rice.It is estimated that each year more than 10m hectares(公顷)of agricultural land are lost because salt gets into the soil and stunts(妨碍生长)plants. The problem is caused by several factors. In the tropics , mangroves(红树林)that create swamps(沼泽)and traditionally formed barriers to sea water have been cut down .In the Mediterranean,a series of droughts have caused the water table to drop,allowing sea water to seep(渗透)in. In Latin America , irrigation often causes problems when water is evaporated(蒸发)by the heat , leaving salt deposits behind.Excess salt then enters the plants and prevents them functioning normally.Heavy concentrations of minerals in the plants stop them drawing up the water they need to survive.To overcome these problems,Flowers and Yeo decided to breed rice plants that take in very little salt and store what they do absorb in cells that do not affect the plants' growth.They have started to breed these characteristics into a new rice crop,but it will take about eight harvests before the resulting seeds are ready to be considered for commercial use.Once the characteristics for surviving salty soil are known,Flowers and Yeo will try to breed the appropriate genes into all manners of crops and plants.Land that has been abandoned to na- ture will then be able to bloom again,providing much needed food in the poorer countries of the world. Flowers and Yeo have started a program______.
[多选题]共用题干 第一篇How the First Stars in the Universe Came into ExistenceResearchers believe that our universe began with the Big Bang(宇宙大爆炸)about 13 billion years ago,and that soon after that event,matter began to form as small dust grains and gases.How the first stars formed from this dust and gas has been a burning question for years,but a state-of-the-art computer simula- tion now offers the most detailed picture yet of how these first stars in the universe came into existence.The composition of the early universe was quite different from that of today,and the physics that governed the early universe were also somewhat simpler. Dr. Naoki Yoshida and colleagues in Japan and the U.S.incorporated these conditions of the early universe,sometimes referred to as the"cosmic dark ages",to simulate the formation of an astronomical object that would eventually shine its light into this darkness.The result is a detailed description of the formation of a protostar(原恒星)一the early stage of a mas- sive primordial(原始的)star of our universe , and the researchers ' computer simulation , which has been called a"cosmic Rosetta Stone"sets the bar for further investigation into the star formation process.The ques- tion of how the first stars evolved is so important because their formations and eventual explosions providedthe seeds for subsequent stars to come into being.According to their simulation,gravity acted on minute density variations in matter,gases,and the myste- riou;"dark matter"of the universe after the Big Bang in order to form this early stage of a star一a protostarwith a mass of just one percent of our sun. The simulation reveals how pre-stellar(前恒星的)gases would have actually evolved under the simpler physics of the early universe to form this protostar.Dr. Yoshida's simulation also shows that the protostar would likely evolve into a massive star capable ofsynthesizing(合成)heavy elements,not just in later generations of stars,but soon after the Big Bang."This general picture of star formation,and the ability to compare how stellar objects form in different time periods and regions of the universe,will eventually allow investigation into the origins of life and planets,"said Lars Herriquist,a professor of Astronomy at Harvard University and a co-author of this latest report."The abundance of elements in the universe has increased as stars have accumulated,"he says,"and the formation and destruction of stars continues to spread these elements further across the universe.So all ofthe elements in our bOdies originally formed from nuclear reactions in the centers of stars,long ago."Their simulation of the birth of a protostar in the early universe signifies a key step toward the ambitiousgoal of piecing together the formation of an entire primordial star and of predicting the mass and properties of these first stars of the universe.More powerful computers,more physical data,and an even larger range will be needed for further calculations and simulations,but these researchers hope to eventually extend this simu- lation to the point of nuclear reaction initiation一when a stellar object becomes a true star."Dr. Yoshida has taken the study of primordial star formation to a new level with this simulation,but it still gets us only to the halfway point towards our final goal.It is like laying the foundation of a skyscraper," said Volker Bromm,assistant professor of Astronomy at the University of Texas, Austin and the author of a companion article."We must continue our studies in this area to understand how the initially tiny protostar grows,layer by layer,to eventually form a massive star. But here,the physics become much more complicated and even more computational resources are needed." According to the first two paragraphs,the early universe_______.
[多选题]共用题干 The Cold PlacesThe Arctic is a polar region.It surrounds the North Pole.Like Antarctica,the Arctic is a land of ice and snow.Antarctica holds the record for a low temperature reading-125 degrees Fahrenheit below zero. Reading of 85 degrees below zero is common in both the Arctic and Antarctica.Winter temperatures average 30 degrees below zero in the Arctic .At the South Pole the winter average is about 73 degrees below zero.One thing alone makes it almost impossible for men to live in Antarctica and in parts of the Arctic .This one thing is the low temperature-the killing chill of far North and the polar South.To survive,men must wear the warmest possible clothing. They must build windproof shelters .They must keep heaters going at all times.Not ever for a moment can they be unprotected against the below-zero temperatures.Men have a way of providing for themselves.Polar explorers wrap themselves in warm coats and furs .The cold makes life difficult. But the explorers can stay alive.What about animals?Can they survive?Do we find plants?Do we find life in the Arctic and in Antarctica?Yes,we do. There is life in the oceans.There is life on land.Antarctica,as we have seen,is a cold place indeed.But this has not always been the case.Expedition scientists have discovered that Antarctica has not always been a frozen continent. At one time the weather in Antarctica may have much like our own.Explorers have discovered coal in Antarctica. This leads them to believe that Antarctica at one time was a land of swamps and forests.Heat and moisture must have kept the trees in the forests alive. At one time,the weather in Antarctica was so warm and damp that trees grew there.
[多选题]共用题干 The Differences Among Various Types of AdoptionIn the US,there is a difference between public and private adoption.Public adoption typically involves taking _________ (51) foster(收养的)children and then adopting them after several months.It's significantly less expensive than private or international adoption,but more often than not_______(52)adopting children who are older than 5 or who have_______(53)needs.Private adoptions offer a better chance of adopting newborns,and increasingly,birth parents _______(54)the adoptive parents themselves.That's not a bad idea on its face,as it gives biological parents_______ (55)say in whom they will relinquish(放弃)their children. But this effectively puts_______(56)parents in the position of advertising themselves to birth parents in newspapers and online,_______(57)many couples feel uncomfortable with.Most states allow birth parents to reclaim their children_______(58)the children have been placed with adoptive families,for time periods ranging from a few days in some states to several months in others.Critics of international adoption say this rarely happens.They are only_______ (59)right:it's true that American birth parents don't usually reclaim their children once they've been placed with their adoptive families,but they can and do_______(60)their minds before the papers are signed.International adoption is more expensive than any form of domestic adoption,but in many ways, it is also more straightforward.The_______(61)of a birth parent calling the adoption_______ (62)are effectively zero and while costs are high,they're also determined at the_______(63) and tend not to change as the_______(64)wears on.Couples seeking to adopt should consider all_______(65)and get a range of perspectives before deciding which method is best for them. _________(51)
[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. _________53
[多选题]共用题干 Natural Gas1 Natural gas is produced from reservoirs deep beneath the earth's surface. It is a fossil fuel(矿物燃 料),meaning that it is derived from orgaiiic material buried in the earth millions of years ago.The main corn- ponent of natural gas is methane(甲烷).2 The popularity and use of clean natural gas have increased dramatically over the past 50 years as pipeline infrastructure(基础设施)has been installed to deliver it conveniently and economically to millions of residential,commercial and industrial customers worldwide.Today,natural gas service is available in all 50 states in the U.S.,and is the leading energy choice for fueling American homes and industries.More than 65 million American homes use natural gas.In fact,natural gas is the most economical source for home energyneeds,costing one-third as much as electricity.In addition to heating homes,much of the gas used in the United States is used as a raw material to manufacture a wide variety of products,from paint,to fibers for clothing,to plastics for healthcare,computing and furnishings.Natural gas is also used in a significant number of new electricity-generating power plants.3 Natural gas is one of the safest and cleanest fuels available. It emits(发出)less pollution than other fossil fuel sources. When natural gas is burned , it produces mostly carbon dioxide(二氧化碳)and water va- por一the same substances emitted when humans breathe.Compared with some other fossil fuels,natural gas emits the least amount of carbon dioxide into the air when combusted(燃烧)一making natural gas the clea-nest burning fossil fuel of all.4 The United States consumes about one一third of the world's natural gas output,making it the largest gas-consuming region in the world.The U.S.Department of Energy Information Administration forecasts that natural gas demand will grow by more than 50 percent by 2025.5 There are huge reserves of natural gas beneath the earth's surface.The largest reserves of natural gas can be found in Russia , West and North Africa and the Middle East. LNG(液化天然气)has been pro- duced domestically and imported in the United States for more than four decades.Today,the leading import- ers of LNG are Japan,Korea,France and Spain. Paragraph 2_________
[多选题]共用题干 To Survive or to Vanish1.Over 3.6 billion years ago,the first creature was born in the world.Since then,the earth started its era with life.The history of life on earth has been a history of interaction between living things and their surroundings.To a large extent,the physical form and the habits of the earth's vegetation and its animal life have been molded by the environment. Considering the whole span of earthly time,the opposite effect,in which life actually modifies its surroundings,has been relatively slight. Only in the present century has one species一man acquired significant power to alter the nature of his world.2.During the past 25 years,this power has not only become increasingly great but it has changed in character. The most alarming of all man's assaults upon the environment is the contamination of air,earth,rivers,and sea with dangerous and even lethal materials. This pollution is for the most part irrecoverable.In this now universal contamination of the environment,chemicals are the sinister partners of radiation in changing the very nature of the world the very nature of its life. Chemicals sprayed on croplands or forests or gardens lie long in soil,entering into living organisms, passing from one to another in a chain of poisoning and death.Or they pass mysteriously by underground streams until they emerge and combine into new forms that kill vegetation,sicken cattle,and work unknown harm on those who drink from once pure wells."Man can hardly even recognize the devils of his own creation,"as a scientist has said.3.Hundreds of millions of years have passed before the globe produced the life that now inhabits the earth.Given time not in years but in millennia life adjusts,and a balance has been reached.But in the modern world there is no time.4.The quick steps of change follows the impetuous pace of man rather than the deliberate pace of nature.Radiation is now the unnatural creation of man's tampering with the atom.The chemicals are the synthetic creations of man's inventive mind,having no counterparts in nature.5.To survive these chemicals would require not merely the years of one man's life but the life of generations.And even this,were it by some miracle possible,would be futile,for the new chemicals come from our laboratories in an endless stream;almost five hundred annually find their way into actual use in the United States alone.Among them are many that are used in man's war against nature.Since the mid l940's over 200 basic chemicals have been created for use in killing insects,weeds,and other organisms described as"pests".6.It is not my contention that chemical insecticides must never he used.I do contend that we have put poisonous and biologically potent chemicals indiscriminately into the hands of persons largely or wholly ignorant of their potentials for harm. We have subjected enormous numbers of people to contact with these poisons,without their consent and often without their knowledge.I contend,furthermore,that we have allowed these chemicals to be used with little or no advance investigation of their effect on soil,water,wildlife,and man himself. Future generations are unlikely to forgive our lack of concern for the integrity of the natural world that supports all life. Human's pollution on nature is for the most part_______.
[多选题]共用题干 Obtaining Drinking Water from Air HumidityNot a plant to be seen,the desert ground is too dry.But the air contains water,and research scientistshave found a. __________(51)of obtaining drinking water from air humidity."The process we have developed is based exclusively on renewable energy sources_________(52)thermal solar collectors andphotovoltaic(光电的)cells , ________( 53 ) makes this method completely energy-autonomous. It will ____________( 54 ) function in regions where there is no electrical infrastructure(基础设施),"says Siegfried Egner,head of the research team. The principle of the_________(55)is as follows:hygroscopic(吸湿的) brine(盐水)一saline(含盐的)solution which absorbs moisture一runs down a tower-shaped unit and absorbs water from the air. It is then sucked__________(56)a tank a few meters off the ground in which a vacuum prevails.Energy from solar collectors_________(57)up the brine,which is diluted by the water it has__________ (58).Because of the vacuum,the boiling point of the liquid is lower than it would be under__________(59) atmospheric pressure. The evaporated (蒸发的), non-saline water is condensed and runs down through a completely filled tube in a controlled manner. The gravity of this water column_______(60)produces the vacuum and so a vacuum pump is not needed.The reconcentrated brine________(61)down the tower surface again to absorb moisture from the air."The concept is suitable for various water________(62).Single一person units and plantssupplying water to entire hotels are conceivable,"says Egner. Prototypes have been built for_______(63)system components一air moisture absorption and vacuum evaporation一and the research scientistshave already __________(64)their interplay on a laboratory scale.In a further ________(65)the re- searchers intend to develop a demonstration facility. _________(56)
[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. Carbon nanotubes are currently the most popular topic in materials science.
[多选题]共用题干 Will We Take Vacation in Spaces?When Mike Kelly first set out to build his own private space-ferry service,he figured his bread-and-butter business would be lofting satellites into high-Earth orbit. Now he thinks he may have figured wrong.“People were always asking me when they could go,”says Kelly,who runsKelly Space TechnologT out of San Bernardino,Californi a.“I realized that real market is in space tourism.”According to preliminary market surveys,there are 10,000 would-be-space-tourists willing to spend $1 million each to visit the final frontier. Space Adventure in Arlington,Virginia,has taken more than 1 30 deposits for a two-hour,$98,000 space tour tentatively(and somewhat dubiously)set to occur by 2005 .Gene Meyers of the Space Island Group says:“Space is the next exotic vacation spot.”This may all sound great,but there are a few hurdles.Putting a simple satellite into orbit with no oxygen,life support or return trip necessary already costs an astronomical $22,000/kg.And that doesn't include the cost of insuring rich and possibly litigious passenger. John Pike of theFederation of American Scientists acerbically suggests that the entire group of entrepreneurs trying to corner the space tourism market have between them“just enough money to blow up one rocket.”The U .S.space agency has plenty of money but zero interest in making space less expensive for the little guys.So the little guys are racing to do what the government has failed to do:design a reusable launch system that's inexpensive,safe and reliable.Kelly Space's prototype looks like a plane that has sprouted rocket engines.Rotary Rocket in Redwood City,California,hasa booster with rotors make a helicopter-style return to Earth;Kistler Aerospace in Kirkland,Wash- ington,is piecing together its versions from old Soviet engines,shuttle-style thermal protection tiles and an elaborate parachute system.The first passenger countdowns are still years away,but bureaucrats at the Federal Aviation Administration in Washington are already informally discussing flight regulations.After all,you can't be too prepared for a trip to that galaxy far,far away.For those who are intent on joining the 100-mile high club,Hilton and Budget are plotting to build space hotels.Before the Russian space Mir came down,some people were talking about using it as a low-rent space hotel to reduce the cost. If a space hotel is finally built in space,and if you're thinking of staying in it,you may want to check the Michelin ratings before booking yourself a suite. We can infer from the context that the Michelin ratings can help people to find prices of hotels.
[多选题]共用题干 The Cold PlacesThe Arctic is a polar region.It surrounds the North Pole.Like Antarctica,the Arctic is a land of ice and snow.Antarctica holds the record for a low temperature reading-125 degrees Fahrenheit below zero. Reading of 85 degrees below zero is common in both the Arctic and Antarctica.Winter temperatures average 30 degrees below zero in the Arctic .At the South Pole the winter average is about 73 degrees below zero.One thing alone makes it almost impossible for men to live in Antarctica and in parts of the Arctic .This one thing is the low temperature-the killing chill of far North and the polar South.To survive,men must wear the warmest possible clothing. They must build windproof shelters .They must keep heaters going at all times.Not ever for a moment can they be unprotected against the below-zero temperatures.Men have a way of providing for themselves.Polar explorers wrap themselves in warm coats and furs .The cold makes life difficult. But the explorers can stay alive.What about animals?Can they survive?Do we find plants?Do we find life in the Arctic and in Antarctica?Yes,we do. There is life in the oceans.There is life on land.Antarctica,as we have seen,is a cold place indeed.But this has not always been the case.Expedition scientists have discovered that Antarctica has not always been a frozen continent. At one time the weather in Antarctica may have much like our own.Explorers have discovered coal in Antarctica. This leads them to believe that Antarctica at one time was a land of swamps and forests.Heat and moisture must have kept the trees in the forests alive. Polar explorers can stay alive without heaters and windproof shelters.
[多选题]共用题干 EcoDormThoreau said education often made straight-cut ditches out of twisting small streams.But not at the EcoDorm,which houses 36 undergraduates and is the spiritual heart of Warren Willege,a liberal arts school of fewer than 1,000 students in Swannanoa,N.C.In recent years,colleges like Warren Wilson took a leading role in the sustainability movement, which seeks to develop a durable human relationship with the environment.More than 600 US colleges and universities have signed up for a pledge to become carbon neutral.Ninety dorms are now LEED certified,the most widely accepted national standard for green design.The EcoDorm is one of only two student residences that have LEED's highest rating.Two Warren Wilson students first proposed the dorm a decade ago.Undergraduates on the planning committee initially suggested that it be built with corncobs or straw. The design,by Asheville一based Samsel Architects, required compromises一as well as a number of creative solutions.The wood used for building the walls was harvested from campus trees that were suffering from a certain disease.The kitchen cabinets were made from recycled fence posts.Rainwater is collected into a disused railway tanker car and pumped back into the house to clean the low-flow toilets.Two toilets,which convert decaying organic matter to fertilizer,are also available on the second floor; students shovel(铲)in wood chips after they use them. The EcoDorm consumes nearly two-thirds less electricity than would a conventional building of the same size.Margo Flood,the executive director of Warren Wilson's Environmental Leadership Center,says those who apply to live there"see an integration between their actions and their values".They pledge not to use hair dryers.Their music does not have its sound made louder electronically. The residents plant and harvest scores of fruits and vegetables in their garden.The EcoDorm's residents speak of the comfort of finding a home where their values are shared. "I didn't have to worry about paper towels being wasted or feeling bad about drying my clothes out-side,"Jeremy Lekich,a senior who oversees the dorm's garden,says."Basically,it has made my life easier." EcoDorms' residents are in common in the aspect of________.
[多选题]共用题干 第三篇Scientists Make Sweet DiscoveryGood news for chocoholics:the treat preferred by millions all over the world is good for you,according to American researchers at the University of California. Chocolate contains substances called flavonoids(类黄 酮)that can help maintain a healthy heart and good circulation.The researchers have discovered that cocoa acts like aspirin and that eating a bar of chocolate once in a while may contribute to a healthy diet. Chocolate has also been shown to release endorphins(内啡肽) in the body: these chemicals help to reduce pain andstress and make you feel happy.But who first discovered this wonderful way of keeping healthy?The Olmec Indians of Mexico and CentralAmerica were the first to grow cocoa beans,in about 1500 BC,and the Mayas were drinking unsweetened cocoa hundreds of years before it became fashionable in Europe.The word chocolate comes from the Nahuatl word xocolati,which means"bitter water".In 1544,a delegation of Mayan nobles visited Philip of Spain and gave him jars of cocoa as a gift. Cocoa soon became fashionable in Spain and Portugal.The Spanish were the first to add sugar to their cocoa drink. In the 17th century,chocolate was becoming fashionable with the middle-classes,not only as a drink but also as a medicine.By the middle of the century,solid chocolate was becoming familiar. In 1753,a Swedish scientist re- named cocoa theobroma or" food for the gods".In 1765,James Baker and John Hanan opened the first choco- late mill in the United States,introducing chocolate to the average citizen.In 1876,in Switzerland,Daniel Peter had the idea of adding milk in the chocolate,making process and produced the first milk chocolate.Since then,chocolate has grown enormously in popularity. One of the biggest chocolate-eating nations isBritain where the average man,woman,and child eats nine kilos of chocolate a year!In fact,chocolate is the number one comfort food and there are more"chocoholics"in Britain than anywhere else in the world.Re- searchers warn that although chocolate is good for you,it should be eaten in small quantities and with noadded milk. Which of the following statements is NOT true according to the passage?
[多选题]共用题干 第一篇Pool WatchSwimmers can drown in busy swimming pools when lifeguards fail to notice that they are in trouble.The Royal Society for the Prevention of Accidents says that on average 15 people drown in British pools each year,but many more suffer major injury after getting into difficulties.Now a French company has developed an artificial intelligence system called Poseidon that sounds the alarm when it sees someone in danger ofdrowning.When a swimmer sinks towards the bottom of the pool,the new system sends an alarm signal to a pool- side monitoring station and a lifeguard's pager."In trials at a pool in Ancenis,near Nantes,it saved a life within just a few months,"says Alistair McQuade,a spokesman for its maker,Poseidon Technologies.Poseidon keeps watch through a network of underwater and overheard video cameras.Al software analy- ses the images to work out swimmers trajectories(轨道,轨线).To do this reliably,it has to tell the difference between a swimmer and the shadow of someone being cast onto the bottom or side of the pool."The under- water environment is a very dynamic one,with many shadows and reflections dancing around."says McQuade.The software does this by"projecting"a shape in its field of view onto an image of the far wall of the pool.It does the same with an image from another camera viewing the shape from a different angle.If the two projections are in the same position,the shape is identified as a shadow and is ignored.But if they are different.the shape is a swimmer and so the system follows its trajectory.To pick out potential drowning victims,anyone in the water who starts to descend slowly is added to the software's "pre-alert"list,says McQuade.Swimmers who then stay immobile on the pool bottom for 5 seconds or more are considered in danger of drowning.Poseidon double-checks that the image really is of a swimmer,not a shadow,by seeing whether it obscures the pool's floor texture when viewed from overhead. If so,it alerts the lifeguard,showing the swimmer's location on a poolside screen.The first full-scale Poseidon system will be officially opened next week at a pool in High Wycombe, Buckinghamshire.One man who is impressed with the idea is Travor Baylis,inventor of the clockwork ra- dio.Baylis runs a company that installs swimming pools一and he was once an underwater escapologist(表演 脱身术的人)with a circus. " I say full marks to them if this works and can save lives , " he says. But h"adds that any local authority spending £30,000一plus a on Poseidon system ought to be investing similar amounts in teaching children to swim. The word"considered"in Paragraph 5 could be best replaced by________.
[多选题]共用题干 A Heroic WomanThe whole of the United States cheered its latest hero,Ashley Smith,with the Federal Bureau of investigation saying it was planning to give a big reward to her for having a brave heart and wise mind.______(46)She was moving into her apartment in Atlanta,Georgia early on the morning of March 12,when a man followed her to her door and put a gun to her side."I started walking to my door,and I felt really,really afraid,"she said in a TV interview last week.The man was BrianNichols , 33 . He was suspected of killing three people at an Atlanta courthouse(法院)on March 11 and later of killing a federal agent.______(47)Nichols tied Smith up with tape,but released her after she repeatedly begged him not to take her life."I told him if he hurt me,my little girl wouldn't have a mummy",she said.In order to calm the man down,she read to him from"The Purpose-Driven Life",a best-selling religious book.He asked her to repeat a paragraph about"what you thought your purpose in life was,what talents were you given.______(48)"I basically just talked to him and tried to gain his trust."Smith said.Smith said she asked Nichols why he chose her. He said he thought"I was an angel sent from God,and we were Christian sister and brother",she said,"And that he was lost,and that God led him to me to tell him that he had hurt a lot of people."______(49)She said Nichols was surprised when she made him breakfast and that the two of them watched television coverage(报道) of the police hunt for him."I cannot believe that's me."Nichols told the woman.Then,Nichols asked Smith what she thought he should do.She said,"I think you should turn yourself in.If you don't,lots more people are going to get hurt."Eventually,he let her go.______(50)A US $ 60,000 reward had been posted for Nichols' capture. Authorities said they did not yet know if Smith would be eligible(有资格的)for that money. ______(50)
[多选题]共用题干 Earth Rocks onMost of the time,the ground feels solid beneath our feet. That{S comforting. But it's also misleading because there's actually a lot going on underground.Masses of land(called plates)slip,slide,and bump against each other,slowly changing the shape of continents and oceans over millions and billions of years.Scientists know that Earth formed about 4.5 billion years ago.They also know that our planet was hot at first. As it cooled , its outermost layer , called the crust(地壳), eventually formed moving plates. Exactly when this shift happened,however,is an open question.Now,an international group of researchers has an answer. They'ye found new evidence suggesting that Earth's crust started shifting at least 3.8 billion years ago.The new estimate is 1.3 billion years earlier than previous ones.Not long before 3. 8 billion years ago,lots of asteroids(小行星)were hitting Earth,keeping its crust in a hot,melted state.After the hard crust formed,much of it sank at various times into the planet's hot in- sides.There,it melted before returning to the surface.In some places,however,the crust never sank.One of the oldest such places is in Greenland,in an area called the Isua supracrustal(上地壳) belt. The rocky crust there is between 3. 7 and 3. 8 billion years old. The belt was once part of the seafloor,but now it is exposed to air.The researchers recently took a close look at the Isua supracrustal belt. They noticed long,parallel cracks in the rock that have been filled in with a type of volcanic rock.To explain this structure,the scientists propose that tension in the crust caused the seafloor to crackopen long ago. Hot , liquid rock , called magma(岩浆),flowed up slowly from deep inside Earth to fill the cracks.Finally,the whole area cooled,forming what we see today.That explanation,plus chemical clues inside the rock,suggests that the Isua supracrustal belt was once part of a plate under the ocean,beginning around 3.8 billion years ago. The formation of the Isua supracrustal belt is thought to have started about 3.8 billion years ago.
[多选题]共用题干 Singing Alarms Could Save the Blind.If you cannot see,you may not be able to find your way out of a burning building-and that could be fatal .A company in Leeds could change all that______(51)directional sound alarms capable of guiding you to the exit.Sound Alert,a company______(52)the University of Leeds,is installing the alarms in a residential home for______(53)people in Sommerset and a resource centre for the blind inCumbria.______(54)produce a wide range of frequencies that enable the brain to determine where the______(55)is coming from.Deborah Withington of Sound Alert says that the alarms use most of the frequencies that can be______(56)by humans."It is a burst of white noise ______(57)people say sounds like static on the radio,"she says."Its life-saving potential is great."She conducted an experiment in which people were filmed by thermal-imaging cameras trying to find their way out of a large______(58)room. It______(59)them nearly four minutes to find the door______(60)a sound alarm,but only 15 seconds with one.Withington studies how the brain______(61)sounds at the university. She says that the _______(62)of a wide band of frequencies can be pinpointed more easily than the source of a narrow band .Alarms______(63)the same concept have already been installed on emergency vehicles.The alarms will also include rising or falling frequencies to indicate whether people should go up______(64)down stairs.They were______(65)with the aid of a large grant from British Nuclear Fuels. 56._________
[多选题]共用题干 A Special JourneyI am often asked to describe the experience of_______(51)a child with a disability一to try to help people who have not shared that unique experience to understand it,to imagine how it would feel.It's like this…_______(52)you're going to have a baby,it's like planning a fabulous vacation trip to Italy. You buy a bunch of guide books and make your wonderful_______(53).The Coliseum,the Michelangelo,David,the gondolas in Venice.You may learn some handy phrases in Italian. It's all very exciting.After months of eager anticipation,the day finally_______(54).You pack your bags and _______(55)you go.Several hours later,the plane lands.The_______(56)comes in and says,"Welcome to Holland.""Holland?"you say."What do you mean by Holland?I signed up for Italy!I'm supposed to be in Italy. All my life I've dreamed_______(57)going to Italy."But there's been a change in the flight plan.They've landed in Holland and there you must stay.The important thing is that they haven't taken you to a horrible,disgusting,filthy place,full of pestilence,_______(58)and disease.It's just a_______(59)place._______(60)you must go out and buy new guide books.And you must learn a whole new language.And you will meet a whole new group of people you would never have met.It's just a different place.It's slower-paced than Italy,less flashy than Italy. But after you've been there for a while and you catch your breath,you look around…and you begin to_______ (61)that Holland has windmills…and Holland has tulips.Holland even has Rembrandts.But everyone you know is busy coming and going_______(62)Italy…and they're all bragging about_______(63)a wonderful time they had there. And for the rest of your life,you will say"Yes,that's where I was_______(64)to go.That's what I had planned."But if you spend your life_______(65)the fact that you didn't get to Italy,you may never be free to enjoy the very special,the very lovely things about Holland. _________(60)
[多选题]共用题干 Will We Take Vacation in Spaces?When Mike Kelly first set out to build his own private space-ferry service,he figured his bread-and-butter business would be lofting satellites into high-Earth orbit. Now he thinks he may have figured wrong.“People were always asking me when they could go,”says Kelly,who runsKelly Space TechnologT out of San Bernardino,Californi a.“I realized that real market is in space tourism.”According to preliminary market surveys,there are 10,000 would-be-space-tourists willing to spend $1 million each to visit the final frontier. Space Adventure in Arlington,Virginia,has taken more than 1 30 deposits for a two-hour,$98,000 space tour tentatively(and somewhat dubiously)set to occur by 2005 .Gene Meyers of the Space Island Group says:“Space is the next exotic vacation spot.”This may all sound great,but there are a few hurdles.Putting a simple satellite into orbit with no oxygen,life support or return trip necessary already costs an astronomical $22,000/kg.And that doesn't include the cost of insuring rich and possibly litigious passenger. John Pike of theFederation of American Scientists acerbically suggests that the entire group of entrepreneurs trying to corner the space tourism market have between them“just enough money to blow up one rocket.”The U .S.space agency has plenty of money but zero interest in making space less expensive for the little guys.So the little guys are racing to do what the government has failed to do:design a reusable launch system that's inexpensive,safe and reliable.Kelly Space's prototype looks like a plane that has sprouted rocket engines.Rotary Rocket in Redwood City,California,hasa booster with rotors make a helicopter-style return to Earth;Kistler Aerospace in Kirkland,Wash- ington,is piecing together its versions from old Soviet engines,shuttle-style thermal protection tiles and an elaborate parachute system.The first passenger countdowns are still years away,but bureaucrats at the Federal Aviation Administration in Washington are already informally discussing flight regulations.After all,you can't be too prepared for a trip to that galaxy far,far away.For those who are intent on joining the 100-mile high club,Hilton and Budget are plotting to build space hotels.Before the Russian space Mir came down,some people were talking about using it as a low-rent space hotel to reduce the cost. If a space hotel is finally built in space,and if you're thinking of staying in it,you may want to check the Michelin ratings before booking yourself a suite. Kelly hoped to develop space tourism,which he thought would be a good market.
[多选题]共用题干 The Impact of Antarctic Ozone HoleThe Antarctic ozone(臭氧)hole is changing weather patterns across the Southern Hemisphere (半球),even affecting the tropics,scientists have concluded. The scientists______(51)the new study added the ozone hole into standard climate models to_______(52)how it might have affected winds and rains. They say rainfall has moved further south towards the pole and the effect has been_______(53)strong over Australia.And of_______(54)interest was the southward of the Southern Hemisphere jet stream. These high一altitude winds are_______(55)to determining weather patterns,in both hemispheres. Much of the cold weather felt in the UK_______(56)the last couple of winters,for example,was caused by blocking of the Northern Hemisphere stream.The team found that overall,the ozone hole has_______(57)in rainfall moving south along with the winds._______(58)there are regional differences,particularly concerning Australia. In terms of the average for that zone,the ozone hole_______(59)about a 10% change一but for Australia,it's about 35%.Their modeling indicated that global warming_______(60)greenhouse gas emissions is also a factor in changing rainfall patterns.Natural climate cycles are also thought to be important here,as different rainfall patterns were _______(61)in the era before ozone depletion(消耗)and late 20th Century warming.Although the_______(62)international organization has significantly checked emissions of harmful substances,they_______(63)for decades in the atmosphere,and so their effects are still being felt.Earlier,and international organization forecast that even the Antarctic ozone hole一which is more severe than its_______(64)in the Northern Hemisphere一should be_______(65)by 2045—2060. _________(59)
[多选题]共用题干 Tightened Visa RegulationsAccording to South Korea's new visa regulations,native speakers of English in South Korea will be required to undergo criminal record checks,medical and drug tests,provide sealed academic transcripts(成绩单)and have their university diplomas inspected,The Korea Times has reported.The tightened regulations will affect an estimated 17,000 foreigners that hold E-2 visas specifically for foreign language teachers.The most controversial requirement is that English teachers residing(居住)outside South Korea will have to have an interview at a South Korean Embassy before taking up their teaching posts. For applicants living in remote areas in Canada,Australia or the US,this is an additional travel burden .Meanwhile,foreign teachers currently living in South Korea must leave the country after their one-year contracts and renew their visas by visiting a neighboring country and return without additional documentation(文件证据).The visa changes are a reaction to public concern about the suitability of some foreign teachers .A report from the South Korean Ministry of Education and Human Resources Development shows between 2001 and August of this year,1,481 foreign language teachers have been caught for a range of offenses including forged(伪造的)degrees , visa violations and general lawbreak-ing.But the changes are likely to slow up the supply of teachers to South Korea's English language education sector. According to Michael Duffy,manager of a teacher placement service in South Korea,applicants have to spend a few hundred dollars and several months on getting affidavits(书面陈述书)for documents. " South Korea has put up too many hoops(圈)to jump through,"he said,adding that foreigners would seek work elsewhere.Most foreigners wonder if the experience of working in South Korea will be worth the burden of the paper work and increasing restrictions."I don't think(South)Korea has thought this through."Said Scott Mclnnis,a Canadian teacher based in Incheon near Seoul."This is a reactionary move by the government that will have strong implications for the EFL community."As part of the efforts to ease the discontent(不满),the South Korean Ministry of Justice has granted a three-month grace period for current E-2 visa holders to prepare the necessary docu- ments. It can be inferred from paragraph 2 that before the visa regulations were revised,foreign teachers have to______.
[多选题]共用题干 第三篇Hurricane(飓风)KatrinaA hurricane is a fiercely powerful , rotating(旋转的)form of tropical storm that can be 124 to 1,240 miles in diameter. The term hurricane is derived from Hurican,the name of a native American storm god.Hurricanes are typical of a calm central region of low pressure between 12 to 60 miles in diameter,known as the eye.They occur in tropical regions.Over its lifetime,one of these can release as much energy as 10,000 nuclear bombs.The seed for hurricane formation is a cluster(聚集)of thunderstorm over warm tropical waters. Hurricanes can only form and be fed when the sea一surface temperature exceeds 27℃and the surrounding atmosphere is calm. These requirements are met between June and November in the northern part of the world.Under these conditions, large quantities of water evaporate (蒸发)and condense(冷凝)into clouds and rain一releasing heat in the process.It is this heat energy,combined with the rotation of the Earth,that drives a hurricane.When the warm column of air from the sea surface first begins to rise,it causes an area of low pressure.This in turn creates wind as air is drawn into the area. This spinning wind drags up more moist air from the sea surface in a process that strengthens the storm. Cold air falls back to the ocean surface through the eye and on the outside of the storm.Initially,when wind speeds reach 23 miles per hour,these mild,wet and grey weather systems are known as depressions,or low air pressure.Hurricane Katrina formed in this way over the south-eastern Bahamas on 23 August 2005.Katrina has had a devastating impact on the Gulf Coast of the U.S.,leaving a disaster zone of 90,000 square miles in its wake(尾迹)—almost the size of the U.K.Thousands have been killed or injured and more than half a million people have become homeless in a humanitarian(人道主义的)crisis of a scale not seen in the U. S. since the Great Depression.The cost of the damage may top$100 billion. Which of the following is NOT a"requirement"for the formation of a hurricane?
[多选题]共用题干 Sharks Perform a Service for Earth's WatersIt is hard to get people to think of sharks as anything but a deadly enemy.They are thought to ______(51)people frequently .But these fish perform a______(52)service for earth's waters and for human beings .Yet business and sport fishing are threatening their______(53).Some sharks are at______(54)of disappearing from earth.Warm weather may influence both fish and shark activity.Many fish swim near coastal areas ______(55)their warm waters. Experts say sharks may follow the fish into the same areas, ______(56)people also swim.In fact,most sharks do not purposely charge at or bite humans.They are thought to mistake a person______(57)a sea animal,such as a seal or sea lion.That is why people should not swim in the ocean when the sun goes down or comes up .Those are the ______(58)when sharks are looking for food.Experts also say that bright colors and shiny jewelry may cause sharks to attack.A shark has an extremely good sense of smell.It can find small amounts of substances in water,such as blood,body liquids and______(59)produced by animals.These powerful ______(60)help sharks find their food.Sharks eat fish,any______(61)sharks,and plants that live in the ocean.Medical researchers want to learn more about the shark's body defense and immune systems ______(62)disease.Researchers know that sharks______(63)quickly from injuries.They study the shark in hopes of finding a way to fight human disease.Sharks are important for the world's______(64).They eat injured and diseased fish. Their hunting activities mean that the numbers of other fish in ocean waters do not become too ______(65).This protects the plants and other forms of life that exist in the oceans. 65._________
[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! Which of the following statements is true of the Northern Lights?
[多选题]共用题干 The Cold PlacesThe Arctic is a polar region.It surrounds the North Pole.Like Antarctica,the Arctic is a land of ice and snow.Antarctica holds the record for a low temperature reading-125 degrees Fahrenheit below zero. Reading of 85 degrees below zero is common in both the Arctic and Antarctica.Winter temperatures average 30 degrees below zero in the Arctic .At the South Pole the winter average is about 73 degrees below zero.One thing alone makes it almost impossible for men to live in Antarctica and in parts of the Arctic .This one thing is the low temperature-the killing chill of far North and the polar South.To survive,men must wear the warmest possible clothing. They must build windproof shelters .They must keep heaters going at all times.Not ever for a moment can they be unprotected against the below-zero temperatures.Men have a way of providing for themselves.Polar explorers wrap themselves in warm coats and furs .The cold makes life difficult. But the explorers can stay alive.What about animals?Can they survive?Do we find plants?Do we find life in the Arctic and in Antarctica?Yes,we do. There is life in the oceans.There is life on land.Antarctica,as we have seen,is a cold place indeed.But this has not always been the case.Expedition scientists have discovered that Antarctica has not always been a frozen continent. At one time the weather in Antarctica may have much like our own.Explorers have discovered coal in Antarctica. This leads them to believe that Antarctica at one time was a land of swamps and forests.Heat and moisture must have kept the trees in the forests alive. The lowest temperature that man has ever known was recorded in Antarctic
[多选题]共用题干 The Impact of Antarctic Ozone HoleThe Antarctic ozone(臭氧)hole is changing weather patterns across the Southern Hemisphere (半球),even affecting the tropics,scientists have concluded. The scientists______(51)the new study added the ozone hole into standard climate models to_______(52)how it might have affected winds and rains. They say rainfall has moved further south towards the pole and the effect has been_______(53)strong over Australia.And of_______(54)interest was the southward of the Southern Hemisphere jet stream. These high一altitude winds are_______(55)to determining weather patterns,in both hemispheres. Much of the cold weather felt in the UK_______(56)the last couple of winters,for example,was caused by blocking of the Northern Hemisphere stream.The team found that overall,the ozone hole has_______(57)in rainfall moving south along with the winds._______(58)there are regional differences,particularly concerning Australia. In terms of the average for that zone,the ozone hole_______(59)about a 10% change一but for Australia,it's about 35%.Their modeling indicated that global warming_______(60)greenhouse gas emissions is also a factor in changing rainfall patterns.Natural climate cycles are also thought to be important here,as different rainfall patterns were _______(61)in the era before ozone depletion(消耗)and late 20th Century warming.Although the_______(62)international organization has significantly checked emissions of harmful substances,they_______(63)for decades in the atmosphere,and so their effects are still being felt.Earlier,and international organization forecast that even the Antarctic ozone hole一which is more severe than its_______(64)in the Northern Hemisphere一should be_______(65)by 2045—2060. _________(58)
[多选题]共用题干 InflationBusiness and government leaders also consider the inflation rate to be an important general indicator. Inflation is a period of increased spending that causes rapid rises in prices._______(51)your money buys fewer goods so that you get_______(52)for the same amount of money as before,inflation is the problem. There is a general rise_______(53)the price of goods and services.Your money buys less.Sometimes people describe inflation as a time when"a dollar is not worth a dollar anymore".Inflation is a problem for all consumers.People who live on a fixed income are hurt the _______(54).Retired people,for instance,cannot count on an increase in income as prices rise. Elderly people who do not work face serious problems in stretching their incomes to_______(55) their needs in time of inflation.Retirement income_______(56)any fixed income usually does not rise as fast as prices.Many retired people must cut their spending to_______(57)rising prices.In many cases they must stop_______(58)some necessary items,such as food and clothing. Even _______(59)working people whose incomes are going up,inflation can be a problem. The_______(60)of living goes up,too. People who work must have even more money to keep up their standard of living. Just buying the things they need costs more.When incomes do not keep _______(61)with rising prices,the standard of living goes down.People may be earning the same amount of money,but they are not living as well because they are not able to buy as many goods and services.Government units gather information about prices in our economy and publish it as price indexes _______(62)the rate of change can be determined.A price index measures changes in prices using the price for a_______(63)year as the base.The base price is set at 100,and the other prices are reported as a_______(64)of the base price.A price index makes_______(65)possible to compare current prices of typical consumer goods,for example,with prices of the same goods in previous years. _________(53)
[多选题]共用题干 第二篇DepressionAlthough the stigma(耻辱)once associated with mental illness has gradually gone away in recent years,most of the Americans who have clinical depression still don't get treated for it partly because many are too embarrassed to go to a psychologist. In fact,the majority of depressed people who seek professional help turn first not to a psychologist but to their primary care physician.But do regular doctors really know how to identify depression?A large new scientific review suggests they don't. In a review of 41 previous studies,the authors found that general practitioners make frequent mistakes,missing true cases of depression about half the time and incorrectly diagnosing it in 19%of healthy people.Alex Mitchell,Amol Vaze and Sanjay Rao of Leicester General Hospital in the U.K. estimate that about 1 in 5 people in developed nations will experience depression in their lifetime.That means that among a general patient population of 100,about 20 will develop the condition,but the typical doctor will find it in only 10 of those who have it. And among the 80 healthy people,the doctor will incorrectly identify depression in 15.This is significant because depression can make the patient and his or her family weak.Depression also carries an enormous social burden,leading to missed work days,loss of productivity and increases in health-care spending. Further,those misdiagnosed with depression may end up being prescribed medicine that not only costs a lot but can have serious side effects.The various studies that Mitchell,Vaze and Rao reviewed used different methods to verify whether doctors had missed depression in their patients.Virtually all the studies pointed to the same conclusion:general physicians aren't very good at recognizing the most common mental illness in the world.Why?One reason is that the typical doctor visit is quite short,usually no longer than 15 minutes.It's hard for patients to open up about their symptoms during that brief period.Doctors should spend more time or schedule follow-up appointments with patients they suspect have depression, which would dramatically increase the rate of accurate diagnoses. Those who"will develop the condition"(Line 3,Par
[多选题]共用题干 The Fridge1.The fridge is considered a necessity.It has been so since the l960s when packaged food first appeared with the label:"Store in the refrigerator."2.In my fridgeless fifties childhood,I was fed well and healthily.The milkman came daily,the grocer,the butcher,the baker,and the ice-cream man delivered two or three times a week.The Sunday meat would last until Wednesday and surplus bread and milk became all kinds of cakes. Nothing was wasted and we were never troubled by rotten food.Thirty years on,food deliveries have ceased,fresh vegetables are almost unobtainable in the country.3.The invention of the fridge contributed comparatively little to the art of food preservation.A vast variety of well-tried techniques already existed一natural cooling,drying,smoking,slating, sugaring,bottling…4.What refrigeration did promote was marketing一marketing hardware and electricity,marketing soft drinks,marketing dead bodies of animals around the globe in search of a good price.5.Consequently,most of the world's fridges are to be found,not in the tropics where they might prove useful,but in the wealthy countries with mild temperatures where they are climatically almost unnecessary.Every winter,millions of fridges hum away continuously,and at vast expanse,busily maintaining an artificially-cooled space inside an artificially一heated house一while outside,nature provides the desired temperature free of charge.6.The fridge's effect upon the environment has been evident,while its contribution to human happiness has been insignificant. If you don't believe me,try it yourself. Invest in a food cabinet and turn off your fridge next winter. You may miss the hamburgers but at least you'll get ride of that terrible hum. The invention of the fridge has not provided a new,economical way in which_______.
[多选题]共用题干 第三篇Oil and EconomyCould the bad old days of economic decline be about to return?Since OPEC agreed to supplycuts in March,the price of crude oil has jumped to almost $26 a barrel,up from less than$10 last December. This near-tripling of oil prices calls up scary memories of the 1973 oil shock,when prices quadrupled,and 1979一1980,when they also almost tripled.Both previous shocks resulted in double-digit inflation and global economic decline.So where are the headlines warning of gloom and doom this time?The oil price was given another push up this week when Iraq suspended oil exports.Strengthening economic growth,at the same time as winter grips the northern hemisphere,could push the price higher still in the short term.Yet there are good reasons to expect the economic consequences now to be less severe than in the l970s.In most countries the cost of crude oil now accounts for a smaller share of the price of petrol than it did in the l970s.In Europe,taxes account for up to four-fifths of the retail price,so even quite big changes in the price of crude have a more muted effect on pump prices than in the past.Rich economies are also less dependent on oil than they were,and so less sensitive to swings in the oil price.Energy conservation,a shift to other fuels and a decline in the importance of heavy, energy-intensive industries have reduced oil consumption.Software,consultancy and mobile telephones use far less oil than steel or car production.For each dollar of GDP(inconstant prices)in rich economies now use nearly 50%less oil than in 1973.The OECD estimates in its latest Economic Outlook that,if oil prices averaged $22 a barrel for a full year,compared with$13 in 1998,this would increase the oil import bill in rich economies by only 0.25%~0.5%of GDP.That is less than one-quarter of the income loss in 1974 or 1980. On the other hand,oil-importing emerging economies一to which heavy industry has shifted一have become more energy-intensive,and so could be more seriously squeezed.One more reason not to lose sleep over the rise in oil prices is that,unlike the rises in the 1970s,it has not occurred against the background of general commodity-price inflation and global excess demand.A sizable portion of the world is only just emerging from economic decline.The Economist's commodity price index is broadly unchanging from a year ago.In 1973 commodity prices jumped by 70%,and in 1979 by almost 30%. It can be inferred from the text that the retail price of petrol will go up dramatically if_______.

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