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1、托福作文写作范文详解ReadingThelittleiceagewasaperiodofusuallycoldtemperatureinmanypartsoftheworldthatlastedfromabouttheyear1350until1900.Therewereunusuallyharshwinters,andglaciersgrewlargerinmanyareas.ScientistshavelongwonderedwhatcausedtheLittleIceAge.Severalpossiblecauseshavebeenproposed.First,thecoolingmay
2、havebeencausedbydisruptingofoceancurrents.BeforetheLittleIceAgeztherewasaperiodofunusuallywarmweatherduringwhichglaciersmelted.ThesemeltedglacierssentalargeamountofcoldfreshwaterintotheGulfStream,alargeoceancurrentthatstronglyaffectsEarthsclimate.Somescientistsbelievethatthisfreshwaterwasenoughtotem
3、porarilydisrupttheGulfStream.SuchadisruptioncouldhavecausedtheLittleIceAge.Second,volcaniceruptioncouldhavecausedtheLittleIceAge.Whenvolcanoeseruptztheysenddarkcloudsofdustandsulfurgasintotheatmosphere.Theseclouds,whichcanspreadovergreatareas,blocksomesunlightfromreachingEarthssurface.Thiscandecreas
4、etheglobaltemperatures.ScientistsknowofseveralvolcaniceruptionsthattookplaceduringtheLittleIceAge.Third,Substantialdecreasesinhumanpopulationsmayhavecontributedindirectlytothecoolingoftheclimate.Foravarietyofreasons(disease,warfare,socialdisruption),thehumanpopulationjustbeforetheLittleIceAgeandduri
5、ngtheearlypartofitwaslowerthanithadbeeninalongtime.Foresttreesstartedgrowingonfieldsthatwerenolongerusedforagriculture.Sincetreesabsorbcarbondioxide,agreenhousegasztheydecreasethegreenhouseeffectthatkeepsEarthwarm.Withmoreforesttreesabsorbingcarbondioxide,Earthbecamecooler.ListeningUnfortunately,the
6、argumentsofthereadingpassagearealittleoutofdate.ScientistsnowhavenewinformationthatshowsthatnoneoftheideasthereadingpassagediscussescouldaccountfortheLittleIceAge.First,abouttheGulfStream.ScientistsnowknowthatdisruptingtheGulfStreamwouldcausecoolingonlyinEuropeandNorthAmerica,buttheLittleIceAgealsoa
7、ffectedtheSouthernhemisphere,inplaceslikeNewZealandandSouthAfricaforexample.SincethedisruptionoftheGulfStreamcannotexplainwhythesesouthernareasbecamecolder,itcannotexplaintheLittleIceAge.Second,thevolcanoestheory.Itzstruethatifvolcaniceruptionsputenoughdustintotheatmosphere,theresultcanbeacoolerclim
8、ate.Butlargeamountsofvolcanicdustintheatmospherewouldhavealsoproducedstrikingvisualeffectthatpeoplewouldhavenoticedatthetime.Forexample,dramaticallycolorfulsunsetsorsnowbeinggreyorbrowninsteadofwhite.ButtherearealmostnoreportsofanythinglikethatroutinelyhappeningduringtheLittleIceAge.Soitseemsthatthe
9、volcaniceruptionsduringthatperiodweresimplynotstrongenoughtoreleasethelargeamountsofdustneededtolowerglobaltemperatures.Third,aboutforestsonfarmlandstoppingthewarminggreenhouseeffectbyremovingcarbondioxide.Therejustwasnotenoughtimeforthiseffecttowork.Thehumanpopulationgrewbacktopreviouslevelsfairlyq
10、uickly,whichmeantthatforestsweresoonbeingcutdownagaintoclearfieldsforthecropsneededtofeedthegrowingpopulation.Asaresult,weknowthattheforestsmentionedinthereadingpassagewerenottherelongenoughtocausethelong-termglobalcoolingoftheclimate.一、阅读听力要点概括ReadingPassagelThecoolingmayhavebeencausedbydisruptingo
11、foceancurrents.2、Second,volcaniceruptioncouldhavecausedtheLittleIceAge.3、Third,Substantialdecreasesinhumanpopulationsmayhavecontributedindirectlytothecoolingoftheclimate.Lecture1、TheGulfStreamwouldcausecoolingdisruptingonlyinEuropeandNorthAmerica,buttheLittleIceAgealsoaffectedtheSouthernhemisphere.2
12、、Largeamountsofvolcanicdustintheatmospherewouldhavealsoproducedstrikingvisualeffectsthatpeoplewouldhavenoticedatthetime.ButtherearealmostnoreportsofanythinglikethatroutinelyhappeningduringtheLittleIceAge.3、Therewasnotenoughtimeforforestsonfarmlandtostopthewarminggreenhouseeffectbyemovingcarbondioxid
13、e.二、范文逐段赏析Paragraph1Inthereadingpassage,theauthorclaimsthatthecauseoftheLittleIceAgewasduetothreemainreasons.Thelecturer,however,refutesthewritersopiniononebyonewithstrongarguments.此段功能首段是总领段，指出了文章与讲座存在不同观点，为接下来的论述做好了铺垫。此段结构此段是并列结构，提出了双方争论的焦点。Paragraph2Firstly,thepassagearguesthattheGulfStreamformed
14、inthepreviouswarmperiodwasresponsiblefortheappearanceoftheunexpectedLittleIceAge.Yetzthespeakerarguesthattheso-calledGulfStreamonlycontributedtothecoolingweatherinNorthernhemispherewhileLittleIceAgetookplaceallovertheworld.ThuszglobalLittleIceAgecannotbeattributedtotheGulfStreaminsomepartsoftheplane
15、tlikeNewZealandandSouthAfrica.此段功能此段提出阅读材料与演讲中的第一个矛盾点。阅读材料认为之前暖季出现的墨西哥湾洋流是导致意外小冰期出现的原因。然而演讲中反驳道，墨西哥湾洋流只可能导致北半球的冷气候，而小冰期事实上在全球范围内都有发生，因此在新西兰和南非等地的小冰期无从解释。此段结构此段是并列结构，分别论述。Paragraph3Next,accordingtothereadingmaterial,dustandsulfurgascausedbyvolcaniceruptionswouldblocksunlight,andthusresultedintheLittl
16、eIceAge.Thelecturer,however,holdsthatvolcaniceruptionsshouldhaveledtoothervisualphenomenathancoolingweather,likecolorfulsunsetsorgreysnow.Butunfortunatelynoneofthemwerereported.Ifthisistakenintoconsideration,volcaniceruptionsdonotseemstrongenoughtoreleasethelargeamountsofdustsneededtolowerglobaltemperatures.此段功能在此段中阅读材料指出另一个观点，即火山爆发引起的灰尘气体等遮住了太阳，进而导致了小冰期。而演讲中指出，如果火山爆发足够巨大，那么应该会有相关报道。因为历史上并没有此方面报道，则说明火山爆发没有那么大规模，也就不可能导致将整个地球温
