高三精品阅读训练科普类新课标试卷
日期：2010-09-04 09:36
科普类Passage1Ifthesalinityofoceanwatersisanalyzed，someofthesesmallchangesareimportantTherearethreebasicprocessesthatcauseachangeinoceanicsalinityOneoftheseisthesubtractionofwaterfromtheoceanbymeansofevaporation—conversionofliquidwatertowatervapourInthismanner，sincethesaltsstaybehindIfthisiscarriedtotheextreme，ofcourse，ishowmuchofthetablesaltweuseisactuallyobtained? ??Theoppositeofevaporationisprecipitation(降水)，bywhichwaterisaddedtotheoceanHeretheoceanisbeingdiluted(冲淡)sothatthesalinityisdecreasedThismayoccurinareasofhighrainfallorincoastalregionswhereriversflowintotheoceanThussalinitymaybeincreasedbythesubstractionofthewaterbyevaporation，whitecrystalsofsaltwouldbeleftbehind;this，ordecreasedbytheadditionoffreshwaterbyprecipitationorrunoff? ??Normally，intropicalregionswherethesunisverystrong，bytheway，suchasrain，thesalinityisincreased，itisfoundtovaryonlyslightlyfromplacetoplaceNevertheless，theoceansalinityissomewhathigherthanitisinotherpartsoftheworldwherethereisnotasmuche，
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