第1页共16页编号：时间：2021年x月x日书山有路勤为径，学海无涯苦作舟页码：第1页共16页英语部分专项练习（一）PartIReadingComprehensionDirections:Thereare4readingpassagesinthispart.Eachpassageisfollowedbysomequestionsorunfinishedstatements.ForeachofthemtherearefourchoicesmarkedA.,B.,C.andD.YoushoulddecideonthebestchoiceandmarkthecorrespondingletterontheAnswerSheetwithasinglelinethroughthecenter.Questions1to5arebasedonthefollowingpassage:Ifthesalinityofoceanwaterisanalyzed,itisfoundtovaryonlyslightlyfromplacetoplace.Nevertheless,someofthesesmallchangesareimportant.Therearethreebasicprocessesthatcauseachangeinoceanicsalinity.Oneoftheseisthesubtractionofwaterfromtheoceanbymeansofevaporation—conversionofliquidwatertowatervapor.Inthismanner,thesalinityisincreased,sincethesaltsstaybehind.Ifthisiscarriedtotheextreme,ofcourse,whitecrystalsofsaltwouldbeleftbehind;this,bytheway,ishowmuchofthetablesaltweuseisactuallyobtained.Theoppositeofevaporationisprecipitation,suchasrain,bywhichwaterisaddedtotheocean.Heretheoceanisbeingdilutedsothatthesalinityisdecreased.Thismayoccurinareasofhighrainfallorincoastalregionswhereriversflowintotheocean.Thussalinitymaybeincreasedbythesubtractionofwaterbyevaporation,ordecreasedbytheadditionoffreshwaterbyprecipitationorrunoff.Normally,intropicalregionswherethesunisverystrong,theoceansalinityissomewhathigherthanitisinotherpartsoftheworldwherethereisnotasmuchevaporation.Similarly,incoastalregionswhereriversdilutethesea,salinityissomewhatlowerthaninotheroceanicareas.Athirdprocessbywhichsalinitymaybealteredisassociatedwiththeformationandmeltingofseaice.Whenseawaterisfrozen,thedissolvedmaterialsareleftbehind.Inthismanner,seawaterdirectlybeneathfreshlyformedseaicehasahighersalinitythanitdidbeforetheiceappeared.Ofcourse,whenthisicemelts,itwelltendtodecreasethesalinityofthesurroundingwater.IntheWeddellSea,offAntarctica,thedensestwaterintheoceansisformedasaresultofthisfreezingprocess,whichincreasesthesalinityofcoldwater.Thisheavywatersinksandisfoundinthedeeperportionsofoceansoftheworld.1.Whatisthemaintopicofthepassage?A.Wheredowegetourtablesalt?B.OceanicsalinityintropicalregionsC.ThreebasicprocessesthatalteroceanicsalinityD.Variationsofsalinityindifferentpartsoftheocean第2页共16页第1页共16页编号：时间：2021年x月x日书山有路勤为径，学海无涯苦作舟页码：第2页共16页2.Accordingtotheauthor,theoceanicsalinityisusuallylowerin_____.A.tropicalregionsB.coastalregionsC.placesinwhichwarmcurrentsandcoldcurrentsmeetD.theAntarctica3.Allofthefollowingareprocessesthatdecreaseoceansalinityexcept_____.A.precipitationB.runoffC.meltingD.evaporation4.Whatdoestheword“subtraction"inthefourthlineofthefirstparagraphmean?A.reductionB.influxC.transformationD.freezing5.WhichofthefollowingisNOTaresultoftheformationoficeinoceans?A.Thesurroundingwatersinks.B.Thewaterbecomesdenser.C.Watersalinitydecreases.D.Thesurroundingwaterbecomescolder.Questions6to10arebasedonthefollowingpassage:Morethanacenturyago,therelationshipbetweenglacialiceandtheamountofwaterintheoceanbasinswasfirstseen.Whenthegreaticesheetcoveredvastlandareas,thesealevelwasloweredbecausethenormalreturnofwaterfromlandtotheoceanwasreduced.Asaresult,thesealevelroseasIceAgeglaciersmeltedallowingthemeltedwaterstoflowintotheocean.Ifalltheglacialiceonthesurfaceoftheearthtodayshouldmelt,thesealevelmightrisebymorethan150feet.Shorelinevariations...
