北京市成人英语三级真题

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1、2011年05月07日　　PartIReadingComprehension(30%)　　Directions:Therearethreepassagesinthispart.Eachpassageisfollowedbysomequestionsorunfinishedstatements.ForeachofthemtherearefourchoicesmarkedA,B,CandD.Youshoulddecideonthebestchoiceandblackenthecorrespondingle

2、tterontheAnswerSheet。　　Passage1　　QuestionsIto5arebasedonthefollowingpassage:　　Spending50minuteswithacellphoneclosetoyourearisenoughtochangebraincellactivityinthepartofthebrainclosesttotheantenna(天线).Butwhetherthatcausesanyharmisnotclear,scientistsattheN

3、ationalInstituteofHealthsaidataconferencelastmonth,addingthatthestudywillnotlikelysettleconcernsofalinkbetweencellphonesandbraincancer.“Whatweshowedisglucose(葡萄糖)metabolism(代谢)(asignofbrainactivity)increasesinthebraininpeoplewhowereexposedtoacellphonein

4、theareaclosesttotheantenna,”saidDr.NoraVolkowoftheNIH,whosestudywaspublishedintheJournaloftheAmericanMedicalAssociation.(76)Thestudywasmeanttoexaminehowthebrainreactstoelectromagneticfieldscausedbywirelessphonesignals。　　Volkowsaidshewassurprisedthatthew

5、eakelectromagneticradiation(电磁辐射)fromcellphonescouldaffectbrainactivity,butshesaidthefindingsdonotshedanylightonwhethercellphonescausecancer.“Thisstudydoesnotinanywayindicatethat.Whatthestudydoesistoshowthehumanbrainissensitivetoelectromagneticradiation

6、fromcellphoneexposures。”Useofthedeviceshasincreaseddramaticallysincetheywereintroducedintheearly1980s,withabout5billioncellphonesnowinuseworldwide。　　Somestudieshavelinkedcellphoneexposuretoanincreasedriskofbraincancers,butalargestudybutheWorldHealthOrga

7、nizationdidnotofferaclearanswertothis.Volkow’steamstudied47peoplewhohadtheirbrainexaminedwhileacellphonewasturnedonfor50minutesandanotherwhilethephonewasturnedoff.Whiletherewasnocompletechangeinbrainmetabolism,theyfounda7percentincreaseinbrainmetabolism

8、intheregionclosesttothecellphoneantennawhenthephonewason。　　(77)Expertssaidtheresultswereinteresting,buturgedthattheybeunderstoodwithgreatcare.“Althoughthebiologicalsignificance,ifany,ofincreasedglucosemetabolismfromtoomuchcellpho