距离2017年6月大学英语四级考试还有一个半月的时间，已经报名的同学备考一定要抓紧，不要临时抱佛脚。新东方网英语四级频道为大家整理了英语四级阅读理解每日一练，每天一道题考试不担心。
Ifthepopulationoftheearthgoesonincreasingatitspresentrate,therewilleventuallynotbeenoughresourceslefttosustainlifeontheplanet.Bythemiddleofthe21stcentury,ifpresenttrendscontinue,wewillhaveusedupalltheoilthatdrivesourcars,forexample.Evenifscientistsdevelopnewwaysoffeedingthehumanrace,thecrowdedconditionsonearthwillmakeitnecessaryforlustolookforopenspacesomewhereelse.Butnoneoftheotherplanetsinoursolarsystemarecapableofsupportinglifeatpresent.Onepossiblesolutiontotheproblem,however,hasrecentlybeensuggestedbyAmericanscientist,ProfessorCarlSagan.
Saganbelievesthatbeforetheearth'sresourcesarecompleetelyexhausteditwillbepossibletochangetheatmophereofVenusandsocreateanewworldalmostaslargeasearthitself.ThedifficultisthatVenusismuchhotterthantheearthandthereisonlyatinyamountofwaterthere.
Saganproposesthatalgaeorganismsthatcanliveinextremelyhotorcoldatmospheresandatthesametimeproduceoxygen,shouldbebredinconditionsimilartothoseonVenus.Assoonasthishasbeendone,thealgaewillbeplacedinsmallrockets.SpaceshipwillthenflytoVenusandfiretherocketsintotheatmosphere.Inafairlyshorttime,thealgewillbreakdownthecarbondioxideintooxygenandcarbon.
Whenthealgaehavedonetheriwork,theatmospherewillbecomecooler,butbeformancansetfootonVenusitwillbeneccessaryfortheoxygentoproducerain.ThesurfaceoftheplanetwillstillbetoohotformantolandonitbuttherainwilleventuallyfallandinafewyearssomethinglikeearthwillbereproducedonVenus.
1.Intelongrun,themostinsolubleproblemcausedbypopulationgrowthonearthwillprobablybethelackof______.
2.CarlSaganbelievesthatVenusmightbecolonizedfromearthbecause_____
a.itmightbepossibletochangeitsatmosphere
b.itsatmosphereisthesameastheearth's
c.thereisagoodsupplyofwateronVenus
d.thedaysonVenusarelongenough
3.OnVenusthereisalotof________.
4.Algaeareplantsthatcan____.
a.liveinveryhottemperatures
b.liveinverycoldtemperatures
5.MancanlandonVenusonlywhen_______.
a.thealgaehavedonetheirwork
b.theatmospherebecomescooler
答案：cabdd
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