托福阅读真题分类——推论题(二).docx

托福阅读真题分类——推论题(二).docx

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时间:2020-08-27

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1、众所周知,托福阅读一直是中国考生的薄弱项,我们为帮助广大托福考生突破阅读瓶颈,提高托福阅读成绩,特地精心整理了托福阅读真题分类素材库。那快来看看托福阅读推论题集锦吧!TheOriginsofCetaceansItshouldbeobviousthatcetaceans—whales,porpoises,anddolphins—aremammals.Theybreathethroughlungs,notthroughgills,andgivebirthtoliveyoung.Theirstreamlinedbodies,

2、theabsenceofhindlegs,andthepresenceofafluke1andblowhole2cannotdisguisetheiraffinitieswithlanddwellingmammals.However,unlikethecasesofseaottersandpinnipeds(seals,sealions,andwalruses,whoselimbsarefunctionalbothonlandandatsea),itisnoteasytoenvisionwhatthefirstwhal

3、eslookedlike.Extinctbutalreadyfullymarinecetaceansareknownfromthefossilrecord.Howwasthegapbetweenawalkingmammalandaswimmingwhalebridged?Missinguntilrecentlywerefossilsclearlyintermediate,ortransitional,betweenlandmammalsandcetaceans.Veryexcitingdiscoverieshavefi

4、nallyallowedscientiststoreconstructthemostlikelyoriginsofcetaceans.In1979,ateamlookingforfossilsinnorthernPakistanfoundwhatprovedtobetheoldestfossilwhale.ThefossilwasofficiallynamedPakicetusinhonorofthecountrywherethediscoverywasmade.Pakicetuswasfoundembeddedinr

5、ocksformedfromriverdepositsthatwere52millionyearsold.TheriverthatformedthesedepositswasactuallynotfarfromanancientoceanknownastheTethysSea.Thefossilconsistsofacompleteskullofanarchaeocyte,anextinctgroupof5ancestorsofmoderncetaceans.Althoughlimitedtoaskull,thePak

6、icetusfossilprovidespreciousdetailsontheoriginsofcetaceans.Theskulliscetacean-likebutitsjawboneslacktheenlargedspacethatisfilledwithfatoroilandusedforreceivingunderwatersoundinmodernwhales.Pakicetusprobablydetectedsoundthroughtheearopeningasinlandmammals.Theskul

7、lalsolacksablowhole,anothercetaceanadaptationfordiving.Otherfeatures,however,showexpertsthatPakicetusisatransitionalformbetweenagroupofextinctflesh-eatingmammals,themesonychids,andcetaceans.IthasbeensuggestedthatPakicetusfedonfishinshallowwaterandwasnotyetadapte

8、dforlifeintheopenocean.Itprobablybredandgavebirthonland.AnothermajordiscoverywasmadeinEgyptin1989.Severalskeletonsofanotherearlywhale,Basilosaurus,werefoundinsediment

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