职称英语直播课-完形填空讲义—3.10日 (1)

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1、（一）SeeingRedMeansDangerAheadC级Thecolorredoftenmeansdanger—andbypayingattention,accidentscanbeprevented.Inthefuture,thecolorredalsomayhelp_____(51)dangeratconstructionsites.Thankstonewworkbyengineers,bridgesupports—or________(52)kindsofmaterials—couldonedaycontainacolor-changingm

2、aterial.Itwillturnred________(53)astructurecollapsesorfallsapart.Thesecret________(54)thecolor-changingmaterialisaparticulartypeofmolecule（分子）.Amoleculeisagroupofatoms（原子）heldtogetherbychemicalbonds.Moleculescome________(55)allshapesandsizes,andmakeup________(56)youcansee,toucho

3、rfeel.Howamoleculebehavesdependson________(57)kindsofatomsitcontains,andhowthey’reheldtogether.Whenapolymer（聚合物）containingacolor-changingmoleculecalledamechanophore（机械响应性聚合物）isabouttobreak,itproducesa________(58).Whenapolymerwithmechanophoremoleculesbecomes“injured”or________(59

4、),oneofthemechanophorebonds________(60)andthematerialturnsred.“It’sareallysimpledetectionmethod,”saysNancySottos,oneofthescientistswhoworkedontheproject.Sottosandherteamtestedthecolor-changingpolymersintheirlab.Thetest________(61)provedencouraging.Thereisawaytogetridoftheredcolo

5、r:light.Whenabrightlightisshoneonthemechanophore,thebrokenbondisfixed—andtheredcolor________(62).This“self-healing”maybeaproblemforengineers.Theyneedtousethecolor-changerinbigconstructionprojectsthatwillbe________(63),insunlight.Andsunlightwillmakethemechanophore’swarningsystem_

6、_______(64).Sottosandherfellowscientistsstillhave________(65)worktodobeforethecolor-changingmoleculescanbeusedoutsidethelab.51．A．throw            B．prevent          C．create            D．keep52．A．other            B．another            C．theother         D．others53．A．until        

7、      B．although          C．after              D．before54．A．on                B．behind            C．under            D．down55．A．for                B．in                  C．from           D．at56．A．nothing          B．anyone            C．someone          D．everything57．A．why        

8、      B．how              C．what            D．wh