【Nuclearpower’sdangertohealthsafetyandevenlifeitselfcanbesummedupinoneword:radiation.Nuclearradiationhasacertainmysteryaboutitpartlybecauseitcannotbedetectedbyhumansenses.Itcan’tbeseenorheardort】

　　Nuclearpower’sdangertohealthsafetyandevenlifeitselfcanbesummedupinoneword:radiation.

　　Nuclearradiationhasacertainmysteryaboutitpartlybecauseitcannotbedetectedbyhumansenses.Itcan’tbeseenorheardortouchedortastedeventhoughitmaybeallaroundus.Thereareotherthingslikethat.Forexampleradiowavesareallaroundusbutwecan’tdetectthemsensethemwithoutaradioreceiver.Similarlywecan’tsenseradioactivitywithoutaradiationdetector.Butunlikecommonradiowavesnuclearradiationisnotharmlesstohumanbeingsandotherlivingthings.

　　Atveryhighlevelsradiationcankillananimalorhumanbeingimmediatelybykillingmassesofcellsinvitalorgans.Buteventhelowestlevelscandoseriousdamage.Thereisnolevelsofradiationthatiscompletelysafe.Iftheradiationdoesnothitanythingimportantthedamagemaynotbeserious.Thisisthecasewhenonlyafewcellsarehitandiftheyarekilledimmediatelyyourbodywillreplacethedeadcellswithhealthyones.Butifthefewcellsareonlydamagedandiftheyreproducethemselvesyoumaybeintrouble.Theycangrowintocancer.Sometimesthisdoesnotshowupformanyyears.

　　Thisisanotherreasonforsomeofthemysteryaboutnuclearradiation.Seriousdamagecanbedonewithoutthevictimbeingawareatthetimethatdamagehasoccurred.Apersoncanbeirradiated（辐射）andfeelfinethendieforcancerfivetenortwentyyearslaterasaresult.Orachildcanbebornweakasaresultofradiationabsorbedbyitsgrandparents.

　　Radiationcanhurtus.Wemustknowthetruth.

　　【小题1】Whatisthemainideaofthepassage?

　　A．Howtodetectnuclearradiation.B．Howradiationkillaman.C．Themysteryaboutnuclearradiation.D．Seriousdamagecausedbynuclearradiation.【小题2】Whichofthefollowingstatementsistrue? A．Nuclearradiationcancausecancertohumanbeings.B．Nuclearradiationcanbesafetohumanbeingsifitslevelislow.C．Nuclearradiationcanbedetectedbyhumansenses.D．Nuclearradiationisjustlikecommonradiowaves.