托福真题0525Reading人类过度开发历史+热带雨林中动物如何让自己被听到+害虫控制用过文档格式.docx
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托福真题0525Reading人类过度开发历史+热带雨林中动物如何让自己被听到+害虫控制用过文档格式.docx
《托福真题0525Reading人类过度开发历史+热带雨林中动物如何让自己被听到+害虫控制用过文档格式.docx》由会员分享,可在线阅读,更多相关《托福真题0525Reading人类过度开发历史+热带雨林中动物如何让自己被听到+害虫控制用过文档格式.docx(18页珍藏版)》请在冰豆网上搜索。
Overexploitationistheoverusebyhumansofapopulationoforganismstoanextentthatthreatenstheviabilityofthepopulationorradicallyaltersthenaturalcommunityinwhichitlives.Thereisatendencytothinkthatoverexploitationisarelativelynewphenomenon.However,thatviewisabitnaï
ve,aswewillseeinsomeexamplesofpastoverexploitation.
Afterthemostrecentglaciation,whichwasatitsheightbetweenabout20,000and14,000yearsago,thegrasslandsincentralNorthAmericaharboredanextraordinaryarrayoflargeanimals.Thediversityofantelope,horses,cheetahs,giantgroundsloths,mammoths,mastodons,andotheranimalseasilyrivaledthatofthelargeanimalfaunaofAfricatoday.However,about11,000yearsago,attheendofthePleistoceneepoch,manydisappeared;
34generaoflargemammalsbecameextinctinfewerthan1,000years,while40morebecameextinctinSouthAmerica.Thiswasamassivedie-offwhenyouconsiderthatonly20largemammalgenerahadbecomeextinctinNorthAmericaoverthepreviousthreemillionyears.
Isitacoincidencethatsomanylargemammalsbecameextinctshortlyafterthetimethathumans,crossingfromSiberiatoAlaska,probablyfirstarrivedintheWesternHemisphere?
PaulMartin,ananthropologist,thinksnotandhasarguedinmanyarticlesandbooksthatoverhuntingwasprimarilyresponsiblefortheextinctions.Martin’scriticshavearguedthattheextinctionswereprimarilytheresultofsignificantclimatechange.Ifclimatechangewasresponsible,wewouldexpectmanysmallmammals,primarilyrodents,tohavebecomeextinctintheregion,too;
however,onlyfourNorthAmericangeneraofsmallanimalsbecameextinctattheendofthePleistocene,comparedwith46generaovertheprecedingthreemillionyears.Ontheotherhand,perhapssmallmammalsarelesssusceptibletoclimatechangethanlargemammalsare.Wecannotdefinitelysaywhichansweriscorrect,andthetruthmaylieinthemiddle,butmanyscientistsbelievethattheendofthePleistocenesawamassiveoverkillbythefirsthumaninhabitantsoftheAmericas.
Thebestevidencethatoverhuntingbyearlypeopleeliminatedsomespeciescomesfromislands.Onmanyremoteislands,birdsevolvedintheabsenceofmammalianpredators,sometimeslosingtheirabilitytoflyintheprocess.Whenpeoplearrivedontheseislands,theyfoundeasyprey.Forexample,whenPolynesians,nowknownasMaori,arrivedinNewZealandaboutA.D.1200,theislandshad11speciesofmoas:
flightlessbirdsthatrangedinsizefromassmallasaturkeytolargerthananostrich.BythetimeEuropeanscolonizedtheislandsinthe1700s,themoasweregone,alongwithfivespeciesofrailandsixwaterfowlspecies.ThedemiseofthemoasandotherbirdsundoubtedlywashastenedbyforestclearingandotherchangesbroughtaboutbytheMaori,buttheabundanceofmoaremainsatMaorivillagesitesmakesitclearthathuntingwasamajorfactor.
OnsmallislandsthroughoutthePacific,scoresofbirdsareknowntohavebecomeextinctafterthearrivalofPolynesians.IntheHawaiianIslands,44speciesofendemiclandbirdsoutof82becameextinctbetweenthearrivalofPolynesiansandthearrivalofEuropeans.Again,habitatchangeswereundoubtedlyimportant,butitislikelythatoverhuntingwasamajorproblem,especiallyforvariousspeciesofflightlessgeese,ibis,andrail.OnMadagascar,thelosswasnotlimitedtobirds.Thearrivalofpeople1,500to2,000yearsagocausedtheextinctionsoftwogianttortoises,abear-sizedgiantlemur,asmallspeciesofhippopotamus,manyothermammals,andelephantbirds,someofwhichrivaledthelargestmoasinsize.
Currently,theworstoverexploitationmaybehappeningthroughglobaloverfishing.Thisispartiallydisguisedbythefactthatwearestillabletoharvesthugequantitiesofmarinespecies;
onlyoncloserinspectiondoesonenoticethatthepredatoryfishthatusedtodominatecatchesarebeingreplacedbyspeciesfurtherdownthefoodchain.
Paragraph1
1.Theword”viability”inthepassageisclosetinmeaningto
¡
abilitytoexist
mobility
rateofgrowth
abilitytochange
Paragraph2
Paragraph3
2.Accordingtoparagraphs2and3,allofthefollowingaretrueofthediversityoflargemammalsintheNorthAmericangrasslandsafterthemostrecentglaciationEXCEPT:
ItwaseasilyasgreatasthediversityoflargeanimalsinAfricatoday.
Itdiminishedsignificantlyoveraperiodoffewerthan1,000years.
ItwasprobablyreducedbybothclimatechangeandhuntingattheendofthePleistoceneepoch.
ItwasmuchgreaterthanthediversityofsmallanimalpopulationsduringthePleistoceneepoch.
Paragraphs2and3aremarkedwitharrows[→]
3.Whydoestheauthormentionthat“20largemammalgenerahadbecomeextinctinNorthAmericaoverthepreviousthreemillionyears”?
Togiveanexampleofextinctionthatwascausedbyoverexploitationbyhumans
TocastdoubtontheideathattheextinctionsattheendofthePleistoceneepochwereuniqueornotable
ToprovideevidencefortheideathatlargemammalspecieswereabletoflourishincentralNorthAmericaaftertheglaciation
ToemphasizethesignificanceofthenumberofextinctionsattheendofthePleistoceneepoch
4.WhichofthefollowingstatementsbestdescribesanthropologistPaulMartin’sviewsonPleistoceneextinctionasexplainedinparagraph3?
ItisacoincidencethatsomanylargemammalsbecameextinctshortlyafterhumansfirstarrivedintheWesternHemisphere.
OverhuntingwasprimarilyresponsiblefortheextinctionoflargemammalsafterthearrivalofhumansintheWesternHemisphere.
ThemassiveextinctionoflargeanimalspecieswasduetothesevereclimatechangesattheendofthePleistoceneepoch.
Theextinctionoflargemammalswascausedbytheextinctionofsmallrodentsthatlargeanimalshuntedforfood.
Paragraph3ismarkedwithanarrow[→]
5.Whichofthesentencesbelowbestexpressestheessentialinformationinthehighlightedsentenceinthepassage?
Incorrectchoiceschangethemeaninginimportantwaysorleaveoutessentialinformation.
WecannotdefinitelysaywhetherornotamassiveoverkillhappenedattheendofthePleistocene,despitewhatmanyscientistsbelieve.
WecannotdefinitelysaywhetherthemassiveoverkillbythefirsthumaninhabitantsoftheAmericasoccurredinthemiddleoftheendofthePleistocene.
Althoughitisdifficulttoknowforsure,manyscientistsbelievethatthefirsthumaninhabitantswereresponsibleforanoverkillofmammalsattheendofthePleistocene.
ManyscientistsbelievethatmanyofthefirsthumaninhabitantsoftheAmericasdidnotsurvivetheclimatechangesattheendofthePleistocene.
Paragraph5
10.Accordingtoparagr
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- 托福 0525 Reading 人类 过度 开发 历史 热带雨林 动物 如何 自己 听到 害虫 控制
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