第6部分：完形填空(第51～65題，每題1分，共15分) 下面的短文有15處空白，請根據(jù)短文內(nèi)容為每處空白確定1個最佳選項。

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(機械響應性聚合物)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．a(chǎn)nother C．the other D．others

　　53．A．until B．a(chǎn)lthough C．a(chǎn)fter D．before

　　54．A．on B．behind C．under D．down

　　55．A．for B．in C．from D．a(chǎn)t

　　56．A．nothing B．a(chǎn)nyone 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．a(chǎn)bove

　　64．A．dangerous B．useless C．helpful D．important

　　65．A．a(chǎn) part of B．a(chǎn) type of C．a(chǎn) lot of D．a(chǎn) part of

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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

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