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1、托福作文写作范文详解ReadingGeneticmodification,aprocessusedtochangeanorganismsgenesandhenceitscharacteristics,isnowbeingusedtoimprovetreesthroughgeneticmodification.Itispossibletocreatetreesthatproducemorefruitzgrowfaster,orwithstandadverseconditions.Plantinggeneticallymodifiedtreesonalargescalepromisestobrin
2、ganumberofbenefits.First,geneticallymodifiedtreesaredesignedtobeharderthannaturetrees;thatisztheyaremorelikelytosurvivethantheirunmodifiedcounterparts.InHawaii,forexample,anewpestresistantspeciesofpapayatreeshasbeendevelopedinresponsetoringspotvirusinfectionsthathaverepeatedlydamagedthenativepapayat
3、reepopulation.Plantingthegeneticallymodifiedpapayashaslargelyputanendtotheringspotproblem.Moreover,geneticallymodifiedtreespromisetobringanumberofeconomicbenefitstothosewhogrowthem.Geneticallymodifiedtreestendtogrowfaster,givegreateryieldsoffoodzfruitzorotherproductsandbehardier.Thisallowstreefarmer
4、togetfasterandgreaterreturnsontheirfarminginvestmentandsaveonpesticidesaswell.Finally,theuseofgeneticallymodifiedtreescanpreventoverexploitationofwildtrees.Becauseofthegrowingdemandforfirewoodandbuildingtimber,manyforestsaroundtheworldarebeingcutdownfasterthantheycanbereplaced.Introducinggenetically
5、modifiedtrees,designedforfastgrowthandhighyieldingivengeographicconditions,wouldsatisfythedemandforwoodinmanyofthoseareasandsavetheendangerednativetrees,whichoftenincludeuniqueorrarespecies.ListeningSure,therearesomebenefitstoplantgeneticallymodifiedtrees,but,arethesetreesasreallygreatastheyfirstsou
6、nd?Whenyouexaminethesubjectfirstly,therearesomeseriousproblemsandcostsassociatedwithgeneticallymodifiedtrees.First,geneticallymodifiedtreesmayberesistanttooneparticularcondition.Butthatdoesnjtnecessarilyensuretheirsurvival.Youseezatypicalnonmodifiedtreespopulationisgeneticallydiverse.Thatmeansthatfo
7、rmostthreateningconditions,orclimate,whatever,therewillbeatleastsomeindividualtressofanygivenspeciesoftreethatareresistant.Soevenifmostofonekindoftreesarekilled,thosefewresistanttresswillsurviveandensurethesurvivalofthatspeciesoftree.Butgeneticallymodifiedtreesaregeneticallymuchmoreuniform.Soiftheyr
8、eexposedtoanenvironmentalchallengetheyhavenotbeendesignedfor,theyalldie.Soiftheclimatechanges,thegeneticallymodifiedtreeswilllikelytobecompletelywipedout.Nowastothesecondpointzthey,rehiddencostsassociatedwithgeneticallymodifiedtrees.Yousee,thecompanythatgeneticallymodifythetreecanchargetreefarmersmo
9、reforitsseedsthanun-geneticallymodifiedtreeswouldcost.Alsozasyou,vegrownthetree,youcan,tjustcollecttheseedsandplantthenewtreeforfree.ByIawzyouhavetopaythecompanyeverytimeyouplant.Andfinally,geneticallymodifiedtreesmightactuallycauseevenmoredamagetothelocalwildtrees.Youseezgeneticallymodifiedtreesoft
10、engrowmoreaggressivelythannaturaltreesdo.And,geneticallymodifiedtreesaretypicallyplantedamongnaturaltrees.Asaresult,thegeneticallymodifiedtreesOutcompetethenativetreesforresources,sunlight,soil,nutrients,andwater,eventuallycrowdingoutthenaturaltrees.一、阅读听力要点概括ReadingPassageMainpoints:Geneticmodifica
11、tiononlargescalewillbringbenefits.Subpoint1:Canbecompletelywipedoutbycertainenvironment.Subpoint2:Modifiedtreesareeconomicallybetter.Subpoint3:Modifiedtreesgrowfastandsavewildtrees.LectureAttitude:Against(Seriousproblemandassociatedcost.)SubPoint1:ThereareeffectivewaystostopmusselsintodaysknowledgeS
12、ubPoint2:Hiddencostsassociatedlikeseeds.SubPoint3:Domoredamagetowildtrees.GrowsofastandOutcompetethewildtree.二、范文逐段贯析Paragraph1Thelecturerpointsoutthreedifferentshortcomingsofgeneticallymodifiedtrees.Intheaspectsofadaptation,economicIucrativeness,andenvironmentalvalue,theyneverpresentoverwhelmingadv
13、antagescomparedwithnaturaltrees.Thismeansthepointsmadeinthereadingarepartialandbiased.此段功能：（Listeningpassage后文提到用L代替）（Readingpassage后文用R代替）文章首先总结了三个分论点，十分新颖。三个分论点从三方面出发，环境适应性，经济有利性，环保价值性。然后写到L告诉大家R在三个方面的观点都是片面的，改造树和野生树在这三方面的比较并没显出绝对优势。确认了相反的逻辑关系，准备开始辩论。此段结构：此段为分总结构，列举三个要讨论的方面，然后才说L对R的意见,为接下来的辩论做好了充足
14、的准备。Paragraph2First,geneticmodificationdoesnztnecessarilymakeanaturaltreemoreresistanttoenvironmentaladversities.Althoughgeneticmodificationmayallowaspeciestomanifestcertainstrengthsinspecificconditions,asthereadingindicates,thenewtypelacksthegeneticdiversityofanaturalspecies.Thankstothemarginaldiff
15、erencesbetweenindividualtrees,therecanalwaysbesomesurvivorsamongnaturalspeciesfollowingalargeinterruptionlikeclimatechangeorpestinvasion.Butsuchchangesmaycausethedistinctionofageneticallymodifiedspeciesfortheirunificationincharacteristics,decreasingtheiroverallsurvivabilityinmanycases.此段功能：讨论第一个环境适应
16、性方面的论点。L指出改造树并不一定在任何情况下都比野生树更强壮。因为改造树的基因非常单一，而不像野生树一样随机分布。在新恶劣天气情况下，改造树可能因为没有对抗基因而全部死亡,野生树里却千差万别，相对应的个体树会存活而不会导致与灭族。所以改造树的整体存活率是不高的。此段结构：此段为总分结构，陈列证据十分对称，Althoughbut句型很好的列举了相对立的观点和证据。最后证明R之前的论点不可取。Paragraph3Second,treefarmersdonztgetguaranteedeconomicbenefitsiftheyplantgeneticallynewstrains.Companie
17、sthatdevelopnewplantsalwayschargefarmershigherpricesforartificiallyimprovedseedszandreceivemoneyfromfarmerseachtimefarmersgrowthatsameplant.Suchlawsandcompanypoliciescandeprivefarmersofanyeconomicgainmentionedinthereadingpassage.此段功能：第二个经济有利性的讨论中。L的观点是农民使用改造树不一定能有好收益。收益包括成本和产出，改造树成本很高，而且公司会对农民重复收费。这
18、种政策使得R提到的产出高也没有用。此段结构：此段为总分结构，L表明了自己观点后，用了一大段证据支撑改造树的成本高。从而到达了驳倒R的最后收益一定高的道理。Paragraph4Thirdzgeneticallymodifiedtreesdonztpromisetoprotectwildtrees.Infact,sincetheycangrowfasterwithfewerresources,theyaremoreecologicallyinvasivethannormaltrees.Normally,theyareabletooutpaceandstiflethegrowthofnaturalt
19、reesbyusingtheavailablenaturalresourceslikesunshine,waterandsoil.It,sfarfromtheidealisticsituationdescribedinthereading.此段功能：最后，L说改造树不一定能保护野生树。因为改造树由于生长快，所以侵略性强，和野生树同时种植很容易在抢夺资源中抑制野生树，反而没达到R本来保护野生树的目的。此段结构：此段还是总分结构。先表明L的观点，为了证明观点，从生长过程中充分了解了改造树对野生树的可能的危害，从而针锋相对的反驳了R的观点。三、范文全篇总评1 .逻辑结构全文逻辑架构相当严密，第一段就
20、简介指明了要论证的三方面。随后三个论段，对R所说的3个优势进行了批判。在过程中，作者也是严密按照R证明一个观点的顺序，在文中列举L相对应的条件。反驳十分有力。2 .语言表达文中启用了一些生词，句式也十分紧凑，其中值得借鉴的有：1. Intheaspectsofadaptation,economicIucrativenessrandenvironmentalvalue,theyneverpresentoverwhelmingadvantagescomparedwithnaturaltrees.Intheaspectsof（对于A,B,C这几个面来说）,theynever（他们从未，证明，呈现某论点）Adaptation:适应/AdjustmentZModification/Lucrativeness:有利可图的/ProfitabliIityZGainfuIness/2. Distinction:区别,特征，个性Thereisadistinctionbetweenwhathesaysandwhathedoes.3. Deprive:录（J夺，免去/loot/rob/Wehavenorighttodeprivetheirlife.
