WalkthroughtheAmazonraintoresttodayandyouwillfinditsteamywarmdampandthick.Butifyouhadbeentherearound15000yearsagoduringthelasticeagewouldn’tithavebeenthesame?Formorethan30yearsscientisthavebe

　　WalkthroughtheAmazonraintoresttodayandyouwillfinditsteamywarmdampandthick.Butifyouhadbeentherearound15000yearsagoduringthelasticeagewouldn’tithavebeenthesame?Formorethan30yearsscientisthavebeenarguingabouthowrain-forestsmighthavereactedtothecolddryclimateoftheiceagesbuttillnownoonehasreachedasatisfyinganswer.

　　Rain-forestsliketheAmazonareimportantformoppingupCO2fromtheatmosphereandhelpingtosolveglobalwarming.CurrentlythetreesintheAmazontakeinaround500milliontonsofCO2eachyear:equaltothetotalamountofCO2givingoffintheUKeachyear.ButhowwilltheAmazonreacttofutureclimatechange?IfitgetsdrierwillitstillsurviveandcontinuetodrawdownCO2?Scientistshopethattheywillbeabletolearninadvancehowtherainforestwillmanageinthefuturebyunderstandinghowrainforestsreactedtoclimatechangeinthepast.

　　UnfortunatelygettingintotheAmazonrainforestandcollectinginformationareverydifficult.Tostudypastclimatescientistsneedtolookatfossilizedpollen(花粉)keptinlakemud.Goingbacktothelasticeagemeansdrillingdeepdownintolakesediments(沉淀物)whichrequiresspecializedequipmentandheavymachinery.Thereareveryfewroadsandpathsorplacestolandhelicoptersandaeroplanes.Riverstendtobetheeasiestwaytoentertheforestbutthisstillleavesvastaresbetweentheriverscompletelyunsampled(未取样).SofaronlyahandfulofcoreshavebeendrilledthatgobacktothelasticeageandnoneofthemprovideenoughinformationtoprovehowtheAmazonforestreactstoclimatechange.

　　1.Howdoscientistsstudythepastclimatechange?

　　A.Bypredictingtheclimatechangeinthefuture

　　B.bydrillingdowndeepintolandsediments

　　C.Byanalyzingfossilizedpolleninlakemud

　　D.BytakingsamplesfromriversintheAmazon

　　2.Whyisitdifficulttocollectinformationaboutthepastclimatechange?

　　A.Becausescientistscan’tfindproperequipmentandmachinery

　　B.Becauseitisverydifficulttoobtaincompletesamples

　　C.Becausehelicoptersandaeroplaneshavetoplacetoland

　　D.Becausenoneofthecoresprovideanyinformation

　　3.Whereisthepassagemostproba