第6部分：完形填空(第51～65题，每题1分，共15分) 下面的短文有15处空白，请根据短文内容为每处空白确定1个最佳选项。
Seeing Red Means Danger Ahead
The color red often means danger and by paying attention，accidents can be prevented． In thefuture，the color red also may help__________(51)danger at construction sites．Thanks to new workby engineers，bridge supports or_________(52)kinds of materials could one dav contain a colorswitching material．It will turn red__________(53)a structure collapses or falls apart．
The secret_________(54)the color switching material is a particular type of molecule(分子)． A molecule 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 mole． cule behaves depends on___________(57)kinds of atoms it contains，and how thev're held together．
When a polymer(聚合物)containing a color switching molecule called a mechanophore(机械响应性聚合物)which is about to break，it produce a__________(58)．When a polymer withmechanophore molecules becomes"injured"or_______________(59)，one of the mechanophore bonds__________(60)and the material turns red．"It's a really simple detection method．"says NancySottos，one of the scientists who worked on the project． Sottos and her team tested the color switc． hing polymers in their lab．The test__________(61)proved encouraging．
There is a way to get rid of the 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 Problemfor engineers．They need to use the color changer in big construction projects that will be
(63)in sunlight．And sunlight will make the mechanophore's warming system_________(64)． Sottos and her fellow scientists still have______________(65)work to do before．The color switc． hing molecules can be used outside the lab．
51．A．throw B．prevent C．create D．keep
52．A．other B．another C．the other D．others
53．A．until B．although C．after D．before
54．A．on B．behind C．under D．down
55．A．for B．in C．from D．at
56．A．nothing B．anyone C．someone D．everything
57．A．why B．how C．what D．where
58．A.color B．trouble C．what D．where
59．A．strong B．soff C．weak D．time
60．A．closes B．breaks C．increases D．bums
61．A．results B．rules C．tools D．methods
62．A．repairs B．controls C．finishes D．disappears
63．A．inside B．beside C．outside D．above
64．A．dangerous B．useless C．helpful D．important
65．A．a part of B．a type of C．a lot of D．a part of
同时按下Crtl键和A键查看答案
51．B 52．A 53．D 54．B 55．D 56．D 57．C 58．A 59．C 60．B 61．A 62．D 63．C 64．B 65．C
