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1、雅思阅读T/F/NG模拟试题(1) Whenwasthelasttimeyousawafrog?Chancesare,ifyouliveinacity,youhavenotseenoneforsometime.Eveninwetareasonceteemingwithfrogsandtoads,itisbecominglessandlesseasytofindthoseslimy,hoppingandsometimespoisonousmembersoftheanimalkingdom.Allovertheworld,andeveninremotepartsofAustralia
2、,frogsarelosingtheecologicalbattleforsurvival,andbiologistsareatalosstoexplaintheirdemise.Areamphibianssimplyoversensitivetochangesintheecosystem?Coulditbethattheirrapiddeclineinnumbersissignalingsomecomingenvironmentaldisasterforusall? Thisfrighteningscenarioisinparttheconsequenceofadramatic
3、increaseoverthelastquartercenturyinthedevelopmentofoncenaturalareasofwetmarshland；homenotonlytofrogsbuttoallmannerofwildlife.However,asyet,therearenoobviousreasonswhycertainfrogspeciesaredisappearingfromrainforestsinAustraliathathavebarelybeentouchedbyhumanhand.Themysteryisunsettlingtosaythel
4、east,foritisknownthatamphibianspeciesareextremelysensitivetoenvironmentalvariationsintemperatureandmoisturelevels.ThedangeristhatplanetEarthmightnotonlyloseavitallinkintheecologicalfoodchain(frogskeeppopulationsofotherwisepestilentinsectsatmanageablelevels),butwemightbeincreasingouroutputofai
5、rpollutantstolevelsthatmayhavealreadybecomeirreversible.Frogscouldbeinadvertentlywarningusofacatastrophe. Anexampleofaspeciesoffrogthat,atfarasisknown,hasbecomeextinct,istheplatypusfrog.Likethewell-knownAustralianmammalitwasnamedafter,itexhibitedsomeverystrangebehaviour；insteadofgivingbirtht
6、otadpolesinthewater,itraiseditsyoungwithinitsstomach.Thebabyfrogswereactuallybornfromoutoftheirmother"smouth.Discoveredin1981,lessthantenyearslaterthefroghadcompletelyvanishedfromthecrystalclearwatersofBooloumbaCreeknearQueensland"sSunshineCoast.Unfortunately,thisfreakofnatureisnottheonlyfrog
7、speciestohavebeenlostinAustralia.Sincethe1970s,nolessthaneightothershavesufferedthesamefate. Onetheorythatseemstofitthefactsconcernsthedepletionoftheozonelayer,awelldocumentedphenomenonwhichhasledtoasharpincreaseinultravioletradiationlevels
