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1、智课网GRE备考资料新GRE考试阅读练习题及答案（九）-智课教育旗下智课教育对于GRE阅读备考，只有多读多练，才能提高语感，积累素材，从而提高阅读理解能力。本文为大家提供新GRE考试阅读练习题，后面附有答案。ClimaticconditionsaredelicatelyadjustedtothecompositionoftheEarth’satmosphere.Iftherewereachangeintheatmosphere—forexample,intherelativeproportionsofatmosphericgases
2、—theclimatewouldprobablychangealso.Aslightincreaseinwatervapor,forinstance,wouldincreasetheheat-retainingcapacityoftheatmosphereandwouldleadtoariseinglobaltemperatures.Incontrast,alargeincreaseinwatervaporwouldincreasethethicknessandextentofthecloudlayer,reducingtheamo
3、untofsolarenergyreachingtheEarth’ssurface.Thelevelofcarbondioxide,CO2,intheatmospherehasanimportanteffectonclimaticchange.MostoftheEarth’sincomingenergyisshort-wavelengthradiation,whichtendstopassthroughatmosphericCO2easily.TheEarth,however,reradiatesmuchofthereceivede
4、nergyaslong-wavelengthradiation,whichCO2absorbsandthenremitstowardtheEarth.Thisphenomenon,knownasthegreenhouseeffect,canresultinanincreaseinthesurfacetemperatureofaplanet.AnextremeexampleoftheeffectisshownbyVenus,aplanetcoveredbyheavycloudscomposedmostlyofCO2,whosesurf
5、acetemperatureshavebeenmeasuredat430℃.IftheCO2contentoftheatmosphereisreduced,thetemperaturefalls.Accordingtoonerespectabletheory,iftheatmosphericCO2concentrationwerehalved,theEarthwouldbecomecompletelycoveredwithice.Anotherequallyrespectabletheory,however,statesthatah
6、alvingoftheCO2concentrationwouldleadonlytoareductioninglobaltemperaturesof3℃.If,becauseofanincreaseinforestfiresorvolcanicactivity,theCO2contentoftheatmosphereincreased,awarmerclimatewouldbeproduced.Plantgrowth,whichreliesonboththewarmthandtheavailabilityofCO2wouldprob
7、ablyincrease.Asaconsequence,plantswouldusemoreandmoreCO2.EventuallyCO2levelswoulddiminishandtheclimate,inturn,wouldbecomecooler.Withreducedtemperaturesmanyplantswoulddie;CO2wouldtherebybereturnedtotheatmosphereandgraduallythetemperaturewouldriseagain.Thus,ifthisprocess
8、occurred,theremightbealong-termoscillationintheamountofCO2presentintheatmosphere,withregulartemperatureincreasesandde
