118号托福浏览真题答案解析.docx
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1、11.8号托福浏览真题答案解析11.8号托福浏览真题答案解析本文关于2017年11月18日浏览真题回忆,有利于考生备考温习。让我们回忆一下近期考试的内容:环境类,生物类,词汇题等,请考生们要认真的浏览哦,来学习啦会给你不一样的精彩内容,学习啦会在考试后第一时间更新。11.8号托福浏览答案解析浏览部分考试回忆如下:1.PreventingOvergrowthamongTreeBranchesshedding剪枝的意义。一个是由于有些树枝消耗掉的碳物质比生产的多,另一个原因是有时候气候很干,剪枝减少水的消耗。词汇题补充:exposed=unprotectedwithnowarning=withou
2、tanyindicationbeforehandcongestion=overcrowding2.CrownofThornsStarfishandCoralReefs冠状棘海星,话题重复2020.01.08珊瑚的消失和一种海星的数量猛增有关系,主要讲的是导致猛增的原因(环境+人)词汇题补充:outbreak=suddenincreaseaccompany=occuralongwithconverge=cometogetherseverity=seriousness原题重现:Thecrownofthornsstarfish,AcanthasterTlanci,islarge,twenty-fiv
3、etothirty-fivecentimetersindiameter,andhasseventotwenty-onearmsthatarecoveredinspines.ItfeedsprimarilyoncoralandisfoundfromtheIndianOceantothewestcoastofCentralAmerica,usuallyatquitelowpopulationdensities.Sincethemid-1950s,populationoutbreaksatdensitiesfourtosixtimesgreaterthannormalhaveoccurredatth
4、esametimeinplacessuchasHawaii,Tahiti,Panama,andtheGreatBarrierReef.Theresulthasoftenbeenthelossofafiftypercenttonearlyonehundredpercentofthecoralcoveroverlargeareas.AsingleAcanthastercanconsumefivetosixsquaremetersofcoralpolypsperyear,anddensepopulationscandestroyuptosixsquarekilometersperyearandmov
5、eonrapidly.Acanthastersshowapreferenceforbranchingcorals,especiallyAcroporids.Afteranoutbreakinaparticulararea,itiscommontofindthatAcroporidshavebeenselectivelyremoved,leavingamosaicoflivinganddeadcorals.InplaceswhereAcroporidspreviouslydominatedthecommunitydevastationcanbealmostcomplete,andlocalare
6、asofreefshavecollapsed.Areasofdeadcoralareusuallycolonizedrapidlybyalgaeandoftenarelatercolonizedbyspongesandsoftcorals.Increasesinabundanceofplant-eatingfishanddecreasesinabundanceofcoral-feedingfishaccompanythesechanges.Corallarvaesettleamongthealgaeandeventuallyestablishflourishingcoralcolonies.I
7、ntentofifteenyearsthereefsoftenreturntoaboutthesamepercentageofcoralcoverasbefore.Developmentofafour-speciesdiversitytakesabouttwentyyears.Twoschoolsofthoughtexistconcerningthecauseoftheseoutbreaks.Onegroupholdsthattheyarenaturalphenomenathathaveoccurredmanytimesinthepast,citingoldmensrecollectionso
8、fearlieroutbreaksandevidencefromtraditionalcultures.Theothergroupmaintainsthatrecenthumanactivitiesrangingfromphysicalcoraldestructionthroughpollutiontopredatorremovalhavetriggeredtheseevents.Onetheory,theadultaggregationhypothesis,maintainsthatmostspeciesismoreabundantthanwerealizewhenastormdestroy
9、scoralandcausesafoodshortage.TheadultAcanthastersconvergeonremainingportionsofhealthycoralandfeedhungrily.CertainlytherehavebeenoutbreaksofAcanthasterfollowinglargestorms,butthereislittleevidencethatthestormshavecausedtheenoughreefdamagetocreateafoodshortageforthesestarfish.Twootherhypothesesattempt
10、toexplaintheincreasedabundanceofAcanthasterafterepisodesofhighterrestrialrunofffollowingstorms.Thefirsthypothesisisthatlowsalinityandhightemperaturesfavorthesurvivalofthestarfishlarvae.Thesecondhypothesisemphasizesthefoodwebaspect,suggestingthatstrongfreshwaterrunoffbringsadditionalnutrientstothecoa
11、stalwaters,stimulatingphytoplanktonproductionandpromotingmorerapiddevelopmentandbettersurvivalofthestarfishlarvae.Thosefavoringanthropogenic(humaninfluenced)causeshavepointedtothelargeproportionofoutbreaksthathavebeennearcentersofhumanpopulations.Ithasbeensuggestedthatcoralpolypsarethemainpredatorso
12、fthestarfishlarvae.DestructionofcoralbyblastingandotherbadlandusepracticeswouldreducepredationonthestarfishlarvaeandcauseafeedbackinwhichincreasesinAcanthasterpopulationscausestillfurthercoraldestruction.Unfortunately,therearetoofewdocumentedinstancesofphysicaldestructionofcoralbeingfollowedbyoutbre
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