职称英语考试卫生类C阅读基础练习题2018年职称英语考试卫生类C阅读基础练习题Nosuccessinlifemerelyhappens.以下是小编为大家搜索整理的2018年职称英语考试卫生类C阅读基础练习题，希望能给大家带来帮助!更多精彩内容请及时关注我们应届毕业生考试网!Inthe1980s,scientistsaroundtheworldbegantonoticesomethingstrange:Frogsweredisappearing.Morerecentresearchhasshownthatmanykindsofamphibians(两栖动物)aredecliningorhavebecomeextinct.Theyhavebeenaroundforalongtime-over350millionyears.Whyaretheydyingoutnow?Scientistsareseriouslyconcernedaboutthisquestion.Firstofall,amphibiansareanimportantsourceofscientificandmedicalknowledge.Bystudyingamphibians,scientistshavelearnedaboutnewsubstancesthatcouldbeveryusefulfortreatinghumandiseases.Furtherresearchcouldleadtomanymorediscoveries,butthatwillbeimpossibleiftheamphibiansdisappear.Themostseriousaspectofamphibianloss,however,goesbeyondtheamphibiansthemselves.Scientistsarebeginningtothinkaboutwhatamphibiandeclinemeansfortheplanetasawhole.Iftheearthisbecomingunlivableforamphibians,isitalsobecomingunlivableforotherkindsofanimalsandhumanbeingsaswell?Scientistsnowbelievethatamphibiandeclineisduetoseveralenvironmentalfactors.Oneofthesefactorsisthedestructionofhabitat,thenaturalareawhereananimallives.Amphibiansareverysensitivetochangesintheirhabitat.Iftheycannotfindtherightconditions,theywillnotlaytheireggs.Thesedays,aswildareasarecoveredwithhouses,roads,farms,orfactories,manykindsofamphibiansarenolongerlayingeggs.Forexample,thearroyotoad(蟾蜍)ofsouthernCaliforniawillonlylayitseggsonthesandybottomofaslow-movingstream.ThereareveryfewstreamsleftinsouthernCalifornia,andthosestreamsareoftenmuddybecauseofbuildingprojects.Notsurprisingly,thearroyotoadisnowindangerofextinction.Thereareanumberofotherfactorsinamphibiandecline.Pollutionisoneofthem.Inmanyindustrialareas,airpollutionhaspoisonedtherain,whichthenfallsonpondsandkillsthefrogsandtoadsthatlivethere.Infarmingareas,theheavyuseofchemicalsoncropshasalsokilledoffamphibians.Anotherfactoristhatairpollutionhasledtoincreasedlevelsofultraviolet(UV)light.Thisendangersamphibians,whichseemtobeespeciallysensitivetoUVligh