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1、阅读理解训练题（五十五）AWithouttheatmospheretherewouldbenoweather,nowind,rain,snow,orclouds.Airisallaroundus;weliveatthebottomofagreatoceanofair.Itisinvisible,butwecanfeelitwhenitmoves.Therearemilesofairaboveus,pressingdownwithgreatweightontheearthandeverythingonit.Becauseairpressesdown
2、onusfromalldirectionsatthesametime,andbecauseweareabletobear（忍受）thisweight,wedonotseemtofeelit.Butscientistshaveprovedthatairhasthisweight,andthatanythingthathasweightcreates（产生）aforcecalledpressure.Aschangesinairpressuretakeplace,theymakeairmove.Airisagasthatexpands（膨胀）whenh
3、eated,getslighter,andmovesupward.Whenairiscooled,itgetsheavier,sinksclosetotheearth’ssurface,andflowslikewaterinagreatriver.Aswarmairrises,coldairrushesintotakeitsplace.Thuswindsoriginate（起源）.Thewindsthatblowhighaboveusarecausedbythewarmerairrunningawayfromcolderair.Thewindwe
4、feelneartheearth’ssurfaceistheheavycolderairtryinghardtocatchthewarmerair.Changesintemperaturecausetheairtomove.Andofcoursetherearemanychanges,soairmovementsaretakingplacepracticallyallthetime.56．Thefirstparagraphmainlytellsusthecausesof.A．whywedon’tfeelairB．wheyatmosphereisi
5、mportanttousC．whythereisairsurroundingusD．whythereisairpressure57．Airmovesundersuchconditionsthat.A．thereisairpressureB．theairisheavyC．airpressuredoesn’tremainthesameallthetimeD．aircomesupanddown58．Whichofthefollowingpicturesbesttellsthemovementsofwarmairandcoldair?59．Accordi
6、ngtothepassage,insomeareasiffarmerswhogrowgrapes（葡萄）lightfiresintheearlymorning,thatisbecausethefarmerswantto.A．driveawaywarmairB．preventcoldairfromcomingtoharmtheirplantsC．causemorewindD．stopwarmairrunningawayBAlzheimer’sdiseaseisamajornationalhealthproblem.Nearly2millionAme
7、ricansovertheageof65haveAlzheimer’sdisease.Itisaleadingcauseofdeathamongtheelderly.ButAlzheimer’sdiseaseisnotconfined（限于）totheaged.Theremaybeamillionormorepeopleundertheageof65sufferingfromthedisease.Atonetime,peoplesufferingfromthediseaseweresaidtobe“gettingold”.Thediseasewa
8、sthoughttobeanaturalpartofgrowingold,butitisnowknownthatAlzheimer’sd
