阅读理解更新到50篇

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1、AAnEssentialScientificProcess一个至关重要的科学过程Alllifeontheearthdependsupongreenplants.Usingsunlight,theplantsproducetheirownfood.Thenanimalsfeedupontheplants.Theytakeinthenutrientstheplantshavemadeandstored.Butthat’snotall.Sunlightalsohelpsaplantproduceoxygen.Someoftheoxygenisusedbythepla

2、nt,butaplantusuallyproducesmoreoxygenthanituses.Theexcessoxygenisnecessaryforanimalsandotherorganismstolive.　　Theprocessofchanginglightintofoodandoxygeniscalledphotosynthesis.Besideslightenergyfromthesun,plantsalsousewaterandcarbondioxide.Thewatergetstotheplantthroughitsroots.Thecar

3、bondioxideenterstheleavesthroughtinyopeningscalledstomata.Thecarbondioxidetravelstochloroplasts,specialcellsinthebodiesofgreenplants.Thisiswherephotosynthesistakesplace.Chloroplastscontainthechlorophyllsthatgiveplantstheirgreencolor.Thechlorophyllsarethemoleculesthattraplightenergy.

4、Thetrappedlightenergychangeswaterandcarbondioxidetoproduceoxygenandasimplesugarcalledglucose.　　Carbondioxideandoxygenmoveintoandoutofthestomata.Watervaporalsomovesoutofthestomata.Morethan90percentofwateraplanttakesinthroughitsrootsescapesthroughthestomata.Duringthedaytime,thestomata

5、ofmostplantsareopen.Thisallowscarbondioxidetoentertheleavesforphotosynthesis.Asnightfalls,carbondioxideisnotneeded.Thestomataofmostplantsclose.Waterlossstops.　　Ifphotosynthesisceased,therewouldbelittlefoodorotherorganicmatterontheearth.Mostorganismswoulddisappear.Theearth’satmospher

6、ewouldnolongercontainoxygen.Photosynthesisisessentialforlifeonourplanet.ASunshadeforthePlanet地球防晒霜　　Evenwiththebestwill1intheworld,reducingourcarbonemissionsisnotgoingpreventglobalwarming.Ithasbecomeclearthatevenifwetakethemoststrongmeasurestocontrolemissions,theuncertaintiesinourcl

7、imatemodelsstillleaveopenthepossibilityofextremewarmingandrisesinsealevel.Atthesametime,resistancebygovernmentsandspecialinterestgroupsmakesitquitepossiblethattheactionssuggestedbyclimatescientistsmightnotbeimplementedsoonenough.　　Fortunately,iftheworstcomestotheworse2,scientistssti

8、llhaveafewtricksupt