高中的一道完形填空Withouttheatmoapheretherewouldbenoweather,wind,rain,snoworclouds.Airisallaroundus,weliveatthebottomofagreatoceanofaiir.Itisinvisible,butwecanfeelitwhenitmoves.Therearemilesofaira

　　高中的一道完形填空

　　Withouttheatmoapheretherewouldbenoweather,wind,rain,snoworclouds.Airisallaroundus,weliveatthebottomofagreatoceanofaiir.Itisinvisible,butwecanfeelitwhenitmoves.Therearemilesofairaboveus,pressingdownwithgreatweightontheearthandeverythingonit.Becauseairpressesdownonusfromall__48__atthesametime,andbecauseweareabletobearthisweight,wedonotseemtofeelit,However,scientistahaveprovedthatairhasthisweight,angthat__50__thathasweightcreatesaforcecalledpressure.Aschangesinairpressuretakeplace,theymakeair__51__.

　　Airiaagasthatexpandswhenheats,getslighter,andmoves__52__.Whenairiscooled,itgetsheavier,sinksclosetotheearth'ssurface,andflowslikewaterinagreatriver,Aswarmairrises,coldaierushes__53__tomakeitsplace.Thuswindoriginates.Thewindthatblowsighaboveusiscausedbythewarmerairrunningawayfrom__54__air.Thewindwefeelneartheearth'ssurfaceistheheavycolderairtryinghardto__55__thewarmerair.Changesintemperaturecausetheairtomove.

　　48.AwaysBdirectionsCoceansDrivers

　　50.AeverythingBsomethingCanythingDnothing

　　51.AmoveBriseCfallDstay

　　52.AinwardBdownwardCupwardDoutward

　　53.AoutBinCawayDup

　　54.AcolderBwarmerClighterDheavier

　　55.A.absorbBcatchCfeelDprevent

　　特别是54.55最好有解释，没有也可以