《capillary毛細(xì)管》PPT課件

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1、Unit13Period1ReadingThePropertiesofWaterFindoutasmanywordsandphrasesaspossibleaboutwaterpropertiesinthetext.Skimmingpolarsalinitydensityhighheatcapacityoceanmotion------Waterisaliquidatroomtemperature,andithasarelativelyhighfreezingpoint.Thereasonwhywatercandissolvemostsubstancesonear

2、thisthatwaterhashighheatcapacity.Likealltheothersubstances,watergetssmaller(contract縮小)whenitfreezes.Purewaterhasahigherfreezingpointandlighterthansaltwater.Thesalinityoftheearth’soceansisabout3.5%.Whenwaterfreezes,itsdensityincreases.Otherrecoursessuchasoil,gas,goldetcisaspreciousasa

3、dropofrain.Quiz:TrueorFalseBecausewaterispolargetsexpanddecreasesNothingisaspreciousas---FindoutsomebasicfactsaboutlifeintheoceansScanningBasicfactsaboutlifeintheoceansfromtheopeningparagraph:Lifeonearthbeganintheoceansaboutthreebillionyearsago;99%ofthelivingspaceonearthisintheoceans;

4、Thereareaboutfivemillion(known)speciesintheoceans;Lifeintheoceansrangesfromtinyplanktontogiantwhales.Lifefirstappearedintheblueseas.NaturalselectionAdiverseworld99%ofthelivingspaceonearthisintheoceans.Why?Becausethechemicalstructureofwatermakesitanexcellentmedium(substance/surrounding

5、s)forlife.Howmanyspeciesandhowrich?Fivemillionrangingfromthetiniestplanktonallthewayuptogiantsharksandwhales.Waterisanexcellentmediumforlife.Why?Waterisaliquidatroomtemperatureandhasarelativelyhighfreezingpoint;Alllivingcreaturesneedfoodtosurvive,butonmanyoccasionsthenutrientsbecomeav

6、ailabletolivingthingsonlywhentheyaredissolvedbywater.Waterispolar,itcanbreakdownbothsolidsandgases.Why?Water’suniquechemicalstructureOxygenAtomHydrogenAtomApolarmoleculeWecangetalotofnutrientsbydrinkingsoup.Plantscanpullwateruptheirrootsviaacapillary(毛細(xì)管)process.Canyougivesomeotherexa

7、mpleswhicharealsoresultedfromwater’suniquechemicalstructure?Thesalinityoftheearth’soceansisabout3.5%.Whatdoesthismean?Thereareaboutthirty-fivegrammesofdissolvedsolidsandgasesinonekilogrammeofwater.Inwinterwaterinsomecontainersorsmallriversoftenfreezeswhilewaterinseasnot?Canyouexplainw

8、hy?Th