unit13thewaterplanetwarmingup&speaking课件
日期：2010-12-28 12:23
itcanbreakdownbothsolidsandgasesPutapieceofchalkinwaterforalongtimeWhathappens?Theicecubeputintheglasswithfreshwaterwillfloatinthewater，whatwouldhappen?Withoutwater，Unit13Thewaterplanet(Warmingup&Speaking)LyMiddleSchoolJackKingWhatdotheyhaveincommon?Lead-inWithoutwater，lifewouldnotexistWaterisamusttolifeCommonsenseDoyoulikewater?Howmuchdoyouknowaboutwater?Let’sdosomeexperimentstoknowsomeofthepropertiesofwaterExperimentsexplorationThepieceofpaperwillclingtothecupBecauseoftheairpressureCoveraglassofwaterwithapieceofthickpaperPutonehandonthepaperandturntheglassupsidedownSlowlytakeyourhandawayfromthepaperWhathappens?Why?AOilfloatsonthewaterBWaterfloatsontheoilCTheymixtogetherBecauseofthedifferentdensityofthetwoPourwaterandvegetableoilintoaglassWhathappens?ThechalkwillbedissolvedBecausethewatermoleculeispolar，whiletheoneinsaltwaterwillfloatonthewaterBecauseofthedifferentdensityofthewaterFilloneglasswithfreshwat，
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