雅思阅读测试题.doc

雅思阅读测试题.doc

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1、ReadingREADINGPASSAGE1Youshouldspendabout20minutesonQuestions1-14whicharebasedonReadingPassage1onpages9and10.SpidersilkcutsweightofbridgesAstrong,lightbio-materialmadebygenesfromspiderscouldtransformconstructionandindustryAScientistshavesucceededincopyingthesilk-producinggenesofthe

2、GoldenOrbWeaverspiderandusingthemtocreateasyntheticmaterialwhichtheybelieveisthemodelforanewgenerationofadvancedbio-materials.Thenewmaterial,biosilk,whichhasbeenspunforthefirsttimebyresearchersatDuPont,hasanenormousrangeofpotentialusesinconstructionandmanufacturing.BTheattractionof

3、thesilkspunbythespiderisacombinationofgreatstrengthandenormouselasticity,whichman-madefibreshavebeenunabletoreplicate.Onanequal-weightbasis,spidersilkisfarstrongerthansteelanditisestimatedthatifasinglestrandcouldbemadeabout10mindiameter,itwouldbestrongenoughtostopajumbojetinflight.

4、Athirdimportantfactoristhatitisextremelylight.Armyscientistsarealreadylookingatthepossibilitiesofusingitforlightweight,bullet-proofvestsandparachutes.CForsometime,biochemistshavebeentryingtosynthesizethedrag-linesilkoftheGoldenOrbWeaver.Thedrag-linesilk,whichformstheradialarmsofthe

5、web,isstrongerthantheotherpartsofthewebandsomebiochemistsbelieveasyntheticversioncouldprovetobeasimportantamaterialasnylon,whichhasbeenaroundfor50years,sincethediscoveriesofWallaceCarothersandhisteamusheredintheageofpolymers.DTorecreatethematerial,scientists,includingRandolphLewisa

6、ttheUniversityofWyoming,firstexaminedthesilk-producingglandofthespider.“Wetookouttheglandsthatproducethesilkandlookedatthecodingfortheproteinmaterialtheymake,whichisspunintoaweb.WethenwentlookingforcloneswiththerightDNA,”hesays.EAtDuPont,researchershaveusedbothyeastandbacteriaashos

7、tstogrowtherawmaterial,whichtheyhavespunintofibres.RobertDorsch,Dupont’sdirectorofbiochemicaldevelopment,saystheglobulesofprotein,comparablewithmarblesinanegg,areharvestedandprocessed.“Webreakopenthebacteria,separateouttheglobulesofproteinandusethemastherowstartingmaterial.Withyeas

8、t,thegenesystemcanbedesign

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