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1、托福浏览TPO3(试题+答案+译文)第3篇:TheLong托福浏览TPO3(试题+答案+译文)第3篇:TheLong-TermStabilityofEcosystems为了帮助大家备考托福。提高浏览成绩，打有准备的仗，下面我给大家带来托福浏览TPO3(试题+答案+译文)第3篇:TheLong-TermStabilityofEcosystems，希望大家喜欢。托福浏览原文Plantcommunitiesassemblethemselvesflexibly,andtheirparticularstructuredependsonthespecifichistoryofthearea.Ecologi
2、stsusetheterm“successiontorefertothechangesthathappeninplantcommunitiesandecosystemsovertime.Thefirstcommunityinasuccessioniscalledapioneercommunity,whilethelong-livedcommunityattheendofsuccessioniscalledaclimaxcommunity.Pioneerandsuccessionalplantcommunitiesaresaidtochangeoverperiodsfrom1to500years
3、.Thesechangesinplantnumbersandthemixofspeciesarecumulative.Climaxcommunitiesthemselveschangebutoverperiodsoftimegreaterthanabout500years.Anecologistwhostudiesapondtodaymaywellfinditrelativelyunchangedinayearstime.Individualfishmaybereplaced,butthenumberoffishwilltendtobethesamefromoneyeartothenext.W
4、ecansaythatthepropertiesofanecosystemaremorestablethantheindividualorganismsthatcomposetheecosystem.Atonetime,ecologistsbelievedthatspeciesdiversitymadeecosystemsstable.Theybelievedthatthegreaterthediversitythemorestabletheecosystem.Supportforthisideacamefromtheobservationthatlong-lastingclimaxcommu
5、nitiesusuallyhavemorecomplexfoodwebsandmorespeciesdiversitythanpioneercommunities.Ecologistsconcludedthattheapparentstabilityofclimaxecosystemsdependedontheircomplexity.Totakeanextremeexample,farmlandsdominatedbyasinglecroparesounstablethatoneyearofbadweatherortheinvasionofasinglepestcandestroytheen
6、tirecrop.Incontrast,acomplexclimaxcommunity,suchasatemperateforest,willtolerateconsiderabledamagefromweathertopests.Thequestionofecosystemstabilityiscomplicated,however.Thefirstproblemisthatecologistsdonotallagreewhat“stabilitymeans.Stabilitycanbedefinedassimplylackofchange.Inthatcase,theclimaxcommu
7、nitywouldbeconsideredthemoststable,since,bydefinition,itchangestheleastovertime.Alternatively,stabilitycanbedefinedasthespeedwithwhichanecosystemreturnstoaparticularformfollowingamajordisturbance,suchasafire.Thiskindofstabilityisalsocalledresilience.Inthatcase,climaxcommunitieswouldbethemostfragilea
8、ndtheleaststable,sincetheycanrequirehundredsofyearstoreturntotheclimaxstate.Eventhekindofstabilitydefinedassimplelackofchangeisnotalwaysassociatedwithmaximumdiversity.Atleastintemperatezones,maximumdiversityisoftenfoundinmid-successionalstages,notintheclimaxcommunity.Oncearedwoodforestmatures,forexa
9、mple,thekindsofspeciesandthenumberofindividualsgrowingontheforestfloorarereduced.Ingeneral,diversity,byitself,doesnotensurestability.Mathematicalmodelsofecosystemslikewisesuggestthatdiversitydoesnotguaranteeecosystemstabilityjusttheopposite,infact.Amorecomplicatedsystemis,ingeneral,morelikelythanasi
10、mplesystemtobreakdown.Afifteen-speedracingbicycleismorelikelytobreakdownthanachildstricycle.Ecologistsareespeciallyinterestedtoknowwhatfactorscontributetotheresilienceofcommunitiesbecauseclimaxcommunitiesallovertheworldarebeingseverelydamagedordestroyedbyhumanactivities.Thedestructioncausedbythevolc
11、anicexplosionofMountSt.Helens,inthenorthwesternUnitedStates,forexample,palesincomparisontothedestructioncausedbyhumans.Weneedtoknowwhataspectsofacommunityaremostimportanttothecommunitysresistancetodestruction,aswellasitsrecovery.Manyecologistsnowthinkthattherelativelong-termstabilityofclimaxcommunit
12、iescomesnotfromdiversitybutfromthe“patchinessoftheenvironment,anenvironmentthatvariesfromplacetoplacesupportsmorekindsoforganismsthananenvironmentthatisuniform.Alocalpopulationthatgoesextinctisquicklyreplacedbyimmigrantsfromanadjacentcommunity.Evenifthenewpopulationisofadifferentspecies,itcanapproxi
13、matelyfillthenichevacatedbytheextinctpopulationandkeepthefoodwebintact.托福浏览试题1.Theword“particularinthepassage(paragraph1)isclosestinmeaningtoA.naturalB.finalC.specificDplex2.Accordingtoparagraph1,whichofthefollowingisNOTtrueofclimaxcommunities?A.Theyoccurattheendofasuccession.B.Theylastlongerthanany
14、othertypeofcommunity.C.Thenumbersofplantsinthemandthemixofspeciesdonotchange.D.Theyremainstableforatleast500yearsatatime.3.Accordingtoparagraph2,whichofthefollowingprinciplesofecosystemscanbelearnedbystudyingapond?A.Ecosystempropertieschangemoreslowlythanindividualsinthesystem.B.Thestabilityofanecos
15、ystemtendstochangeasindividualsarereplaced.C.Individualorganismsarestablefromoneyeartothenext.D.Achangeinthemembersofanorganismdoesnotaffectanecosystemsproperties.4.Accordingtoparagraph3,ecologistsoncebelievedthatwhichofthefollowingillustratedthemoststableecosystems?A.PioneercommunitiesB.Climaxcommu
16、nitiesC.Single-cropfarmlandsD.Successionalplantcommunities5.Accordingtoparagraph4,whyisthequestionofecosystemstabilitycomplicated?A.Thereasonsforecosystemchangearenotalwaysclear.B.Ecologistsoftenconfusetheword“stabilitywiththeword“resilience.C.Theexactmeaningoftheword“stabilityisdebatedbyecologists.
17、D.Therearemanydifferentanswerstoecologicalquestions.6.Accordingtoparagraph4,whichofthefollowingistrueofclimaxcommunities?A.Theyaremoreresilientthanpioneercommunities.B.Theycanbeconsideredboththemostandtheleaststablecommunities.C.Theyarestablebecausetheyrecoverquicklyaftermajordisturbances.D.Theyaret
18、hemostresilientcommunitiesbecausetheychangetheleastovertime.7.Whichofthefollowingcanbeinferredfromparagraph5aboutredwoodforests?A.Theybecomelessstableastheymature.B.Theysupportmanyspecieswhentheyreachclimax.C.Theyarefoundintemperatezones.D.Theyhavereduceddiversityduringmid-successionalstages.8.Thewo
19、rd“guaranteeinthepassage(paragraph5)isclosestinmeaningtoA.increaseB.ensureC.favorDplicate9.Inparagraph5,whydoestheauthorprovidetheinformationthat“Afifteen-speedracingbicycleismorelikelytobreakdownthanachildstricycle?A.ToillustrateageneralprincipleaboutthestabilityofsystemsbyusinganeverydayexampleB.T
20、odemonstratethatanunderstandingofstabilityinecosystemscanbeappliedtohelpunderstandstabilityinothersituationsC.Tomakeacomparisonthatsupportstheclaimthat,ingeneral,stabilityincreaseswithdiversityD.Toprovideanexamplethatcontradictsmathematicalmodelsofecosystems10.Theword“palesinthepassage(paragraph6)is
21、closestinmeaningtoA.increasesproportionallyB.differsC.losessignificanceD.iscommon11.Whichofthesentencesbelowbestexpressestheessentialinformationinthehighlightedsentenceinthepassage(paragraph7)?Incurredchoiceschangethemeaninginimportantwaysorleaveoutessentialinformation.A.Ecologistsnowthinkthatthesta
22、bilityofanenvironmentisaresultofdiversityratherthanpatchiness.B.Patchyenvironmentsthatvaryfromplacetoplacedonotoftenhavehighspeciesdiversity.C.Uniformenvironmentscannotbeclimaxcommunitiesbecausetheydonotsupportasmanytypesoforganismsaspatchyenvironments.D.Apatchyenvironmentisthoughttoincreasestabilit
23、ybecauseitisabletosupportawidevarietyoforganisms.12.Theword“adjacentinthepassage(paragraph7)isclosestinmeaningtoA.foreignB.stableC.fluidD.neighboring13.Lookatthefoursquaresthatindicatewherethefollowingsentencecouldbeaddedtothepassage.Infact,damagetotheenvironmentbyhumansisoftenmuchmoreseverethandama
24、gebynaturaleventsandprocesses.【A】Ecologistsareespeciallyinterestedtoknowwhatfactorscontributetotheresilienceofcommunitiesbecauseclimaxcommunitiesallovertheworldarebeingseverelydamagedordestroyedbyhumanactivities.【B】ThedestructioncausedbythevolcanicexplosionofMountSt.Helens,inthenorthwesternUnitedSta
25、tes,forexample,palesincomparisontothedestructioncausedbyhumans.【C】Weneedtoknowwhataspectsofacommunityaremostimportanttothecommunitysresistancetodestruction,aswellasitsrecovery.【D】Wherewouldthesentencebestfit?Clickonasquaretoaddthesentencetothepassage.14.Directions:Anintroductorysentenceforabriefsumm
26、aryofthepassageisprovidedbelow.CompletethesummarybyselectingtheTHREEanswerchoicesthatexpressthemostimportantideasinthepassage.Somesentencesdonotbelonginthesummarybecausetheyexpressideasthatarenotpresentedinthepassageorareminorideasinthepassage.Thisquestionisworth2points.Theprocessofsuccessionandthes
27、tabilityofaclimaxcommunitycanchangeovertime.A.Thechangesthatoccurinanecosystemfromthepioneertotheclimaxcommunitycanbeseeninonehumangeneration.B.Ahighdegreeofspeciesdiversitydoesnotalwaysresultinastableecosystem.C.Thelevelofresilienceinaplantcommunitycontributestoitslong-termstability.D.Ecologistsagr
28、eethatclimaxcommunitiesarethemoststabletypesofecosystems.E.Disagreementsoverthemeaningoftheterm“stabilitymakeitdifficulttoidentifythemoststableecosystems.F.Theresilienceofclimaxcommunitiesmakesthemresistanttodestructioncausedbyhumans.托福浏览答案1.particular十分的，特定的，答案specific。前文讲assemblethemflexibly，多变的，就
29、是每个群落都不一样，强调特殊性。A自然B最终D复杂都与前文不搭，所以都不对2.以climaxcommunities做关键词定位至原文第三句和最后一句，第三句讲明A对，不选;最后一句讲明D对，不选;B没直讲，讲其他的communities变化周期在1-500年，climax最少是500年，讲明climax最长，B对，不选。而且最后一句也讲了climax是变化的，C讲反了，选3.本段非常短，迅速看完之后发现最后一句是结论，讲生态系统比组成生态系统的任意单一物种都稳定，A是答案4.以ecologists做关键词定位至本段第一句，讲生态学家以为生态系统中物种越多越稳定。接着在举例子的时候作者举到了cl
30、imaxcommunities，讲明生态学家以为climaxcommunities最稳定，答案B5.以questionofecosystemstability为关键词定位至本段头两句，讲生态学家对于什么是生态系统的稳定性仍然存在争议，C是原文的忠实改写6.关于climaxcommunities原文有两个地方提到。由于生态学家对什么是稳定这个问题存在两个观点，以不变这种观点看，climax是最稳定的，以快速恢复这种观点看，climax是最不稳定的，所以climax既稳定也不稳定，B明确讲到两个方面，其它选项都只讲到一个方面7.以redwoodforest做关键词定位至原文第三句，事实上这个red
31、wood是前句的一个详细例子，前面句讲至少在温带，mid是最稳定的，不是climax，紧接着就举了一个redwood的例子，能够推断redwood是温带植物，C是答案。A/B/D都与原文意思相反，而且B和D基本上意思一样，都不对8.本句中有个likewise，讲明它与前面句子构成类比，前句讲diversitydoesnotensurestability,后文的内容几乎和前句一模一样，除了动词被替换，因而guarantee的意思就是ensure9.括号的作用是解释括号之前的文字，前文讲系统越复杂越容易坏，后面举了十五速赛车和小孩子的三轮车的例子，三轮车明显比赛车简单，所以就是支持前文，A正确，C
32、正好讲反，其他都没讲10.pale苍白，使什么什么苍白之意。单词所在句之前讲很多climaxcommunities都被人类毁坏了，也就是强调人的破话很严重。后面举了个例子，讲圣海伦斯火山爆发造船的毁坏还没有人类活动的毁坏严重，所以C选项losesignificance正确11.原文的构造是生态系统的长期稳定性不是由于blablabla，而是由于blablabla，又对这个进行了解释，讲物种多;A讲反;B错，由于原文没有讲patchiness和diversity是矛盾的;C错，由于原文比拟的是patchiness和uniform，而C直接将patchiness和clima_行比拟，偷换概念;D正
33、确，注意原文貌似没有明显的因果关系，因而可能单看句子间关系的话会排除D，但原文后半句整个是对patchiness的一种解释，所以存在不明显的因果关系12.adjacent是相邻之意，原文讲本地的population灭绝的话会被哪里来的群落补充，可能的只要foreign和neighboring，这两个选项代入原文都是能够的，除知道这个单词的意思之外，还能够以为相邻的群落更有可能迅速补充，而外来的范围太大，不对13.根据待插入句中的human判定，A/B/C是可能的，naturaleventsandprocesses自然的经过，与第二句中的圣海伦斯火山爆发是同义替换，所以B/C可能正确，但根据先理
34、论后实例的原则，正确答案是B不是C14.Thechanges选项与原文首段的最后一句意思相反，不选Ahighdegree选项对应原文第三段和第五段的首句，第四段的最后一句，正确Thelevel选项对应原文第六段首句，第四段倒数第二第三句，正确Ecologists选项与原文第三段第四段的首句意思相反，不选Disagreements选项对应原文第四段第二句，正确Theresilience选项原文没讲，原文第六段讲不知道为什么生物群落能抵抗毁坏，不选托福浏览译文植物群体能够自由地聚集，它们特殊的构造取决于聚集区域的详细历史。生态学家使用“演替来诠释植物群落和生态系统随着时间推移所发生的变化。演替中的
35、第一个群落被称作先锋群落，而处于演替最后那个长期生存的群落被称为顶极群落。先锋群落和紧接着的植物群落的变化周期是从1到500年不等，植物数量和混合种类数量的变化是渐渐积累的。顶极群落本身也改变，但其变化周期超过500年。当代一个研究池塘的生态学会发现池塘在一年当中相对而言是不变的。个别鱼类可能被替换，但年复一年鱼的总数都趋于一致。也就是讲，一个生态系统本身的属性要比由单一生物体组成的生态系统更稳定。生态学家们一度以为物种的多样性使生态系统稳定，生态系统物种越多样则生态系统越稳定。通过观察得出的结论支持了这个观点，长期持久的顶极群落通常要比先锋群落具备更为复杂的食物网和更多的物种。生态学家家们得
36、出的结论是：顶点生态系统的稳定性明显取决于他们的复杂化程度。举个极端的例子，在单一作物的农田中，一年的恶劣天气或单一害虫的入侵就能够摧毁所有作物。与此相反，在一个复杂的顶极群落里，如温带森林，他们便能够抵御来自气候和害虫的干扰和入侵。不管如何，生态系统稳定性的问题非常复杂。首先，不是所有的生态学家都赞同“稳定的含义。稳定性能够简单地定义为缺乏变化。假如是这样的话，顶极群落将被视为最稳定的，由于根据定义，他们随着时间推移而变化得最少。另外，稳定性可以以界定为生态系统在经历了严重毁坏之后回复原貌的速度，比方火灾。这种稳定性也被称作弹性。在这种情况下，顶极群落将是最脆弱和最不稳定的，由于他们可能需要
37、数百年时间才能恢复到顶点状态。即便是这种被定义为简单地缺乏变化的稳定性并非总是与最多样的物种联络起来。至少在温带地区，会经常在演替经过中发现最多物种，而不是在顶极群落中。例如，红杉树林一旦成熟，其中的物种数量以及单个物种的数量都会减少。一般来讲，多样性本身并不能保证稳定性(事实上正相反)，生态系统的数学模型可以以得出同样的结论。一个更复杂的系统可能比一个简单的系统更容易被毁坏(一个十五速的赛车比一个孩子的三轮车更容易损坏)。生态学家们更想弄清楚到底哪些因素有助于促成群落的恢复，由于世界各地的顶极群落都由于人类活动而遭遭到严重的损坏或毁坏。就像美国西北部圣海伦火山的猛烈喷发所造成的毁坏，在人类活动对环境造成的毁坏面前也相形见绌。我们必须了解对群落抵抗、毁坏和恢复来讲哪些是最重要的。如今的很多生态学家们以为，顶极群落相对长期的稳定性并非来自于多样性，而是来自环境的“补缀，随处变化的环境比始终如一的环境更有利于多种有机体的生存。当地物种灭亡后，马上就会被相邻群落的移民取代。即使是另一种不同的物种，他们可以以填补那些已灭绝生物的空缺，并保持食物网的完好。托福浏览TPO3(试题+答案+译文)第3篇:TheLong-TermStabilityofEcosystems