2014-2015年选修6-Module-5-Cloning语篇提能练习题解析6份5-5

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1、语篇提能Ⅰ.阅读理解Plantcloninghasbeenanagriculturaltechniqueusedbyfarmersandgardenersforcenturies.Grafting(嫁接)isacommonformofplantcloning.Manyplantsinnatureactuallyclonethemselvesandreproduceasexually.Clonedplantsaremuchmorepredictablethannormalplants,sotheiryield(产量)

2、ismorereliable.Clonedplantsalsoreproducefaster，limitingtheamountoftimebetweenplantingandharvesting.Itisalsooftencheapertoproduceseedsthroughcloningthanthroughtraditionalmethods.Plantscanessentiallybeoptimizedsothatfarmersorindividualgrowersalwayshavethebestsee

3、dsavailable.Withhigheryieldatafasterrate,farmscanproducemorefoodformorepeoplewhiledecreasingoverallcosts.Cloningcanbeusedtowipeoutdiseasesthatpreviouslykilledoffentirefieldsofcrops.Thiswouldmakeplantsimmunetothekindsofdiseasesthatfarmersandgardenersaroundthewo

4、rldfeareachyear.Cropfailuresduetodiseaseandviruscouldbecomeathingofthepast.Also,plantsthatarenearextinctioncanbebroughtbacktolifethroughcloning.Throughcloningscientistscandevelopsuperfruitsandvegetablesofsuperior(更好的)nutritionalquality.Thiscouldmakeforahealthi

5、erpopulationoverall.Thishasalreadybeendonethroughselectivepollination(授粉),andgeneticcloningcouldtakeittothenextlevel.Byplantcloningwehaveapopulationofidenticalplantsandalltheseplantsequallysufferfromthesamediseases,butinnaturetheweakwoulddieandthestrongwouldsu

6、rvive.Whiletherearesomedangerstoconsiderwithplantcloning,thereareplentyofbenefitsthatcouldprovevitaltothepropagation(繁衍)ofthehumanspecies.1．Theunderlinedword“optimized”inParagraph2isclosestinmeaningto“______”．A．grown　　　　　　　　B．producedC．perfectedD．examined2．Acc

7、ordingtothetext，clonedplants______.A．haveloweryieldthannormalplantsB．needlesscarefrompeopleC．preventvariouskindsofdiseasesD．haveashortergrowthcycle3．Whatcanweinferfromthetext?A．Thefruitsproducedbyclonedplantstastemuchbetter.B．Therearemoreclonedplantsthannormal

8、plantsnow.C．Plantcloningcandisturbthelawsofnature.D．Peopleshouldavoideatingclonedfruits.4．Whatisthemainpurposeofthetext?A．Towarnthenegativeeffectsofplantcloning.B．Toshowdifferentki