共用题干 Seeing Red Means Danger AheadThe color red often means danger一and by paying attention,accidents...

共用题干
Seeing Red Means Danger Ahead

The color red often means danger一and by paying attention,accidents can be prevented.In the future,
the color red also may help_________（51)danger at construction sites.Thanks to new work by engineers,
bridge supports一or________(52)kinds of materials一could one day contain a color-changing material.It
will turn red_________(53)a structure collapses or falls apart.
The secret__________(54)the color-switching material is。particular typo of molecule（分子）.A mole-
cule is a group of atoms（原子）held together by chemical bonds. Molecules come_________(55)all shapes
and sizes,and make up __________ (56)you can see,touch or feel.How a molecule behaves depends on
_________(57) kinds of atoms it contains,and how they're held together.
When a polymer(聚合物）containing a color-changing molecule called a mechanophore (机械响应性聚
合物）which is about to break,it produces a_________(58).When a polymer with mechanophore molecules
becomes" injured" or__________(59),one of the mechanophore bonds________（60）and the material turns
red."It'S a really simple detection method,"says Nancy Sottos,one of the scientists who worked on the pro-
ject.Sottos and her team tested the color-changing polymers in their lab.The test_________(61)proved
encouraging,
There is a way to get rid of the red color:light. When a bright light is shone on the mechanophore,the
broken bond is fixed,and the red color________(62).This"self-healing"may be a problem for mngi-
neers.They need to use the color-changer in big construction projects that will be_________(63)in sun-
light. And sunlight will make the rnechanophore'S warning system______(64).
Sottos and her fellow scientists still have _________(65)work to do before the color-changing mole-
cules can be used outside the lab. _________(53)