题目内容：
Questions33to36arebasedonthefollowingpassage：
Wouldn'titbegreatifyoucouldjustlookupattheskyandreadtheweatherforecastrightaway？ Well,youCan.Theforecastiswritteninc1ouds.Ifyoucanreadthatwriting，youcantellsomethingabouttheatmosphere.Withsomepractice，youcanbecomeaprettygoodweatherforecaster．Whoknows，youmightevendoaswellasmeteorologists. Meteorologistsusemuchmoreinformationthanjusttheappearanceofthecloudstomaketheirforecast．Theycollectdatafromallovertheworld．Thentheyputitintopowerful，high-speedcomputers. Thisdoesgivemeteorologistsanadvantage，becausetheycantrackweatherpatternsastheymovefromwesttoeastacrossthecountry. Butyouhaveanadvantage，too.Youcanlookattheskyandgetyourdatadirectly．Ameteorologistusesacomputerforecastthat’sseveralhoursoldtomakea1ocalforecast. Whatareyouseeingwhenyoulookatacloud？”Apictureofwhatmoistureisdoingintheatmosphere,”saysmeteorologistPeterLeavit．There’smoisturethroughouttheatmosphere.Mostofthetimeyoudon'tseeit，becauseit'sintheformofaninvisiblegascalledwatervapor. Sometimes，thetemperatureoftheairgetscoldenoughtocausethewatervaportochangetoliquidwater．That’scalledcondensation，andweseeithappenallthetime(forexample，whenhumidairfromtheshowerhitsthecoldglassofamirror).Whenenoughwatervaporcondenses，dropletsformintheair.Thesedropletsscatterlight．Acloudisseen. Watchingc1oudsoveradayortwotellsyoualotmorethanasing1ecloudabouttheweathertocome，Changesincloudsshowchangesintheatmosphere. Youshouldbegintonoticepatterns.Certainclouds，fol1owingeachotherinorder，cansignalanapproachingstorm.Butdon’ttakeourwordforit；seeforyourself. 33．Thispassagemain1ytellsusabouthow__________. A.tobecomeameteorologist B.tokeepaneyeontheweather C.tobeanassistanttoameteorologist D.tochangewatervaportoliquidwater
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