托福作文寫作范文詳解ppo

托福作文寫作范文詳解ReadingAfossilskeletonofadinosaurcalledSinosauropteryx,preservedinvolcanicash,wasdiscoveredinLiaoning,China,in1996.Interestingly,thefossilincludedapatternoffinelinessurroundingtheskeletalbones.SomepaleontologistsinterpretthelinesasevidencethatSinosauropteryxhadfeathers.However,criticshaveopposedtheideathatSinosauropteryxwasafeathereddinosaur,citingseveralreasons.First,thecriticspointsoutthatthefinelinesmaynotevenrepresentfunctionalstructuresofalivingdinosaur,butratherstructuresthatwereformedaftertheanimaTsdeath.Aftertheanimaldiedandwasburiedinvolcanicash,itsskinmayhavedecomposedintofibers.Theskinfibersthenbecamepreservedaslinesinthefossil;thelinesweremisinterpretedasevidenceoffeathers.Second,evenifthefinelinesareremainsofrealstructuresofaSinosauropteryx,scientistscannottellwithcertaintywhatpartofthedinosaur'sanatomythestructureswere.Manydinosaurshadfrills,ornamentalfan-shapedstructuresgrowingoutofsomepartsoftheirbodies.Someofthecriticsarguthatthelinessurroundingtheskeletonaremuchmorelikelytobefossilizedremainsoffrillsthanremainsoffeathers.Athirdobjectionisbasedonthefactthattheusualfunctionsoffeathersaretohelpanimalsflyorregulatetheirinternaltemperature.However,thestructuresrepresentedbythelinesintheSinosauropteryxfossilweremostlylocatedalongthebackboneandthetailoftheanimal.Thiswouldhavemadethestructuresquiteuselessforflightandofverylimiteduseinthermoregulation.Thissuggeststhatthelinesdonotrepresentfeathers.ListeningNowlistentopartofalectureonthetopicyoujustreadabout.ProfessorTheevidencethatthelinesintheSinosauropteryxfossilrepresentfeathersisverystrong.Theargumentsofthecriticsareunconvincing.First,itisunlikelythatthelinesarearesultofthedecompositionofthedinosaur'sskin,becausewedon'tseeanysuchdecompositioninthefossilsofotheranimalsburiedatthesamesite.Infact,thefossilsofmanyotheranimalsburiedatthesiteshowevidencethattheirfunctionalskinstructureshavebeenbeautifullypreservedinvolcanicash.Thewell-preservedconditionoftheotherfossilsmakesitlikelythattheSinosauropteryx^linesarealsowell-preservedfunctionalstructures,possiblyfeathers,andthattheyarenotfiberscausedbydecomposition.Second,theideathatthelinesrepresentfrills..,well,thereisanimportantchemicaldifferencebetweenfeathersandfrills.FeatherscontainagreatdealofaproteincalledBeta-keratin.Frills,ontheotherhand,donotcontainbeta-keratin.OurchemicalanalysessuggestthattheSinosauropteryxstructuresdidcontainbeta-keratin.Sothatindicatesthatthestructureswerefeathers,notfrills.Third,featherscanbeusedforotherfunctionsthanflightandthermoregulation.Thinkofabird,likepeacock,forexample.Thepeacockhaslong,colorfulfeathersinitstail.Anditdisplaysitstailinordertoattractamate.Thafsadistinctfunctionoffeatherscalledthedisplayfunction.Recently,wehavebeenabletodoanalysesontheSinosauropteryxstructuresthatshowusthatthestructureswerecolorful.Theywereorangeandwhite.Thefactthattheywerecolorfulstronglysupportstheideathattheywerefeathersthatthisdinosaurusefordisplay一、閱讀聽力要點概括PassageReadingSomepaleontologistsinterpretthelinesasevidencethatSinosauropteryxhadfeathers.However,criticshaveopposedthisidea.First,thefinelinesmaynotevenrepresentfunctionalstructuresofalivingdinosaur,butratherstructuresthatwereformedaftertheanimaTsdeath.Second,thelinessurroundingtheskeletonaremuchmorelikelytobefossilizedremainsoffrills.AthirdobjectionisthatthestructuresrepresentedbythelinesintheSinosauropteryxfossilwouldhavemadethestructuresquiteuselessforflightandofverylimiteduseinthermoregulation.LectureThecritics'argumentsarenotsoconvincing.First,itisunlikelythatthelinesaretheresultofthedecompositionofthedinosaur'sskinzbecausewedon'tseeanysuchdecompositioninthefossilsofotheranimalsburiedatthesamesite.Second,chemicalanalysissuggeststhattheSinosauropteryxdonotcontainbeta-keratinthatfrillsdonotcontain,butfeathersdo.Feathershaveotherfunctions,likedisplayfunction.二、范文逐段賞析Paragraph1ThereadingpassagerefutestheideathatthelinesintheSinosauropteryxfossilindicatedafeathereddinosaurbydemonstratingseveralcounterarguments.Thelecturer,however,isstronglyconvincedthatlinescouldrepresentfeathersthroughaddressingthequestionsadvancedbythereading.此段功能文章首段概括介紹了閱讀中的觀點，即認為化石中的線條不能顯示這是一只有羽毛的恐龍。而演講者則認為這些線條可以顯示是恐龍的羽毛,指出雙方的矛盾點，為下文論述做好鋪墊。此段結(jié)構(gòu)此段為并列結(jié)構(gòu)，分別陳述了文章和演講中的兩方不同觀點。Paragraph2Tostartwith,accordingtothereading,thoselinesmayderivefromdecompositionofadeaddinosaur'sskininsteadofbeingpartofalivingone.Thelecturerdoesnotbelievethispointforthereasonthatotheranimals1fossilsthatwereburiedatthesamesitehavenotshownsuchkindofdecomposition;instead,theirfunctionalskinstructureshavebeenperfectlypreservedinthevolcanicash.Therefore,theselinesarelikelytobewell-preservedfeathersinsteadoffibers.此段功能指出文章第一個觀點，即認為這些線條是死亡恐龍的皮膚分解腐爛所致,而不是在一只活恐龍身上的一部分。但是演講者反駁道，這一地區(qū)附近的化石上都沒有這種腐爛現(xiàn)象，而且被火山灰保存得很好。由此可以證明這些線條就是恐龍的羽毛。此段結(jié)構(gòu)此段并列結(jié)構(gòu)，指出文章第一個觀點，并提出了演講者的反駁證據(jù)。Paragraph3Movingon,thereadingproposesthatthelinesmaybefrillsratherthanremainsoffeathers.Thelisteningarguesthisisnottrue.Shefurtherexplainsthatthereisanapparentchemicaldifferencebetweenfeathersandfrills.Featherscontainaproteincalledbeta-keratinwhilefrillsdonot.ThechemicalanalysissuggestedthatSinosauropteryx^structurescontaintheproteinbeta-keratin.此段功能指出文章第二個觀點，即這些線條可能是褶皺而非恐龍的羽毛。演講者進一步解釋并反駁了這一點，褶皺和羽毛化學成分不一樣，而化學分析顯示，化石中包含有羽毛中才有的化學成分，以此來證明這些線條是恐龍羽毛。此段結(jié)構(gòu)此段并列結(jié)構(gòu)，指出文章第二個觀點，并提出了演講者的反駁證據(jù)。Paragraph4Lastbutnotleast,thereadingputsemphasisonsuchafactthatlinesaroundthebackboneandthetailoftheSinosauropteryxcannotplaytheroleofhelpingitflyorregulatingitsbodytemperaturebutcommonfeathershavethesefunctions.Thelecturer,bycontrastsme