大学英语 4（专升本阶段）Unit 3.ppt

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大学英语 4（专升本阶段）Unit 3.ppt

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Paras.1-41OnJuly5,1996,aeweataquietresearchfacilityjustoutsideEdinburgh,Scotland,gavebirthtoalamb,knownasDolly,thefirstclonedmammal.Shewastheproductofinsertingacellfromanadultsheep’sudderintoasheepeggfromwhichthenucleushadbeenremoved,thenplacingitinaewetodevelop.2Dollychangedthepublic’sideaofwhatbiotechnologymightdoandimmediatelyposedthequestion:Canhumanclonesbefarbehind?3“Dollywasimportantasasymbolofsciencegoneoutofcontrol,”saysArthurCaplan,directoroftheCenterforBioethicsattheUniversityofPennsylvania.“Peoplewereveryafraidofcloningandwhatitmightmeanintermsofgeneticengineering.”4Adecadelater,thoseconcernsandspeculationshavecooled.Cloningturnsouttobeadifficultproposition.Dollywasthesolesurvivoramong277attemptstocloneasheep.Humancloninghasprovedelusive.5Cloningtoreproduceahumanbeingisnowseenalmostuniversallyastoodangeroustoconsider.Andanimalcloninghasn’tattainedmanyofthegoalsexpectedadecadeago.Stillatleast15mammalshavebeenclonedandresearchcontinues.Butwhatwillthenext10yearsbring?6“Wespentanexcessiveamountoftimearguingoverhumanreproductivecloning10yearsago,butIdon’tthinkthat’sgoingtowindupbeingaveryimportantissue10yearsfromnow,”Dr.Caplansays.“Ithinkthelast10yearshaveshownthatcloningisadifficultprocesstocontrol,oftengoeswrong,andthatmanyofthereasonsitgoeswrongareprobablytieduptothecloningprocessitself.Ithinkthatwillprettywellsealthefateofcloningtomakehumanbeings.Itwillbeunderstoodthatthepricewillbetoohigh.”7About50countrieshavepassedlawsorissuedregulationsagainstcloningtomakehumans.Infact,reproductivecloningiswidelycondemned,evenifonlyonnarrowsafetygrounds.Itshowsthatsomelinescanbedrawnpastwhichsc