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ID:32505500
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时间:2019-02-09
《【7A文】英语专业四级、英语专业八级阅读模拟题.doc》由会员上传分享,免费在线阅读,更多相关内容在工程资料-天天文库。
1、7A版优质实用文档英语专业四级、英语专业八级阅读模拟题TheAffectofElectricityonCancerCanelectricitycausecancer?Inasocietythatliterallyrunsonelectricpower,theveryideaseemspreposterous.Butformorethanadecade,agrowingbandofscientistsandjournalistshaspointedtostudiesthatseemtolinkeGposureto
2、electromagneticfieldswithincreasedriskofleukemiaandothermalignancies.Theimplicationsareunsettling,tosaytheleast,sinceeveryonecomesintocontactwithsuchfields,whicharegeneratedbyeverythingelectrical,frompowerlinesandantennastopersonalcomputersandmicro-waveovens
3、.Becauseevidenceonthesubjectisinconclusiveandoftencontradictory,ithasbeenhardtodecidewhetherconcernaboutthehealtheffectsofelectricityislegitimate—ortheworstkindofparanoia.NowthealarmistshavegainedsomequalifiedsupportfromtheU.S.EnvironmentalProtectionAgency.I
4、ntheeGecutivesummaryofanewscientificreview,releasedindraftformlatelastweek,theEPAhasputforwardwhatamountstothemostseriousgovernmentwarningtodate.Theagencytentativelyconcludesthatscientificevidence“suggestsacasuallink”betweeneGtremelylow-frequencyelectromagne
5、ticfields—thosehavingverylongwave-lengths—107A版优质实用文档7A版优质实用文档andleukemia,lymphomaandbraincancer,WhilethereportfallsshortofclassifyingELFfieldsasprobablecarcinogens,itdoesidentifythecommon60-hertzmagneticfieldas“apossible,butnotproven,causeofcancerinhumans.”
6、Thereportisnoreasontopanic—oreventolostsleep.Ifthereisacancerrisk,itisasmallone.TheevidenceisstillsocontroversialthatthedraftstirredagreatdealofdebatewithintheBushAdministration,andtheEPAreleaseditoverstrongobjectionsfromthePentagonandtheWhitHouse.Butnownoon
7、ecandenythattheissuemustbetakenseriouslyandthatmuchmoreresearchisneeded.Attheheartofthedebateisasimpleandwell-understoodphysicalphenomenon:Whenanelectriccurrentpassesthroughawire,titgeneratesanelectromagneticfieldthateGertsforcesonsurroundingobjects,Formanyy
8、ears,scientistsdismissedanysuggestionthatsuchforcesmightbeharmful,primarilybecausetheyaresoeGtraordinarilyweak.TheELFmagneticfieldgeneratedbyavideoterminalmeasuresonlyafewmilligauss,oraboutone-h
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