2011年北京成人英语三级考试真题.doc

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1、PartIReadingComprehension(30%)　　Directions:Therearethreepassagesinthispart.Eachpassageisfollowedbysomequestionsorunfinishedstatements.ForeachofthemtherearefourchoicesmarkedA,B,CandD.YoushoulddecideonthebestchoiceandblackenthecorrespondingletterontheAn

2、swerSheet.　　Passage1　　QuestionsIto5arebasedonthefollowingpassage:　　Spending50minuteswithacellphoneclosetoyourearisenoughtochangebraincellactivityinthepartofthebrainclosesttotheantenna(天线).Butwhetherthatcausesanyharmisnotclear,scientistsattheNationalIn

3、stituteofHealthsaidataconferencelastmonth,addingthatthestudywillnotlikelysettleconcernsofalinkbetweencellphonesandbraincancer.“Whatweshowedisglucose(葡萄糖)metabolism(代谢)(asignofbrainactivity)increasesinthebraininpeoplewhowereexposedtoacellphoneinthearea

4、closesttotheantenna，"saidDr.NoraVolkowoftheNIH，whosestudywaspublishedintheJournaloftheAmericanMedicalAssociation.(76)Thestudywasmeanttoexaminehowthebrainreactstoelectromagneticfieldscausedbywirelessphonesignals.　　Volkowsaidshewassurprisedthattheweakel

5、ectromagneticradiation(电磁辐射)fromcellphonescouldaffectbrainactivity,butshesaidthefindingsdonotshedanylightonwhethercellphonescausecancer.“Thisstudydoesnotinanywayindicatethat.Whatthestudydoesistoshowthehumanbrainissensitivetoelectromagneticradiationfro

6、mcellphoneexposures.”Useofthedeviceshasincreaseddramaticallysincetheywereintroducedintheearlyl980s，withabout5billioncellphonesnowinuseworldwide.　　Somestudieshavelinkedcellphoneexposuretoanincreasedriskofbraincancers.butalargestudybytheWorldHealthOrgan

7、izationdidnotofferaclearanswertothis.Volkow’steamstudied47peoplewhohadtheirbrainexaminedwhileacellphonewasturnedonfor50minutesandanotherwhilethephonewasturnedoff.Whiletherewasnocompletechangeinbrainmetabolism,theyfounda7percentincreaseinbrainmetabolis

8、mintheregionclosesttothecellphoneantennawhenthephonewason.(77)Expertssaidtheresultswereinteresting,buturgedthattheybeunderstoodwithgreatcare.“Althoughthebiologicalsignificance，ifany,ofincreasedglucosemetabolismfromtoomuchcellphoneexposureisunk