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1、经典：考研英语阅读常规体裁模板分析Model1[生物学类]题目序号题型归类第1题审题定位题型第2题句间关系题型第3题审题定位题型第4题归纳推导题型第5题段落结构题型Thefossilremainsofthefirstflyingvertebrates,thepterosaurs,haveintriguedpaleontologistsformorethantwocenturies.Howsuchlargecreatures,whichweighedinsomecasesasmuchasapilotedhang-gliderandhadwi
2、ngspansfrom8to12meters,solvedtheproblemsofpoweredflight,andexactlywhatthesecreatureswere—reptilesorbirds—areamongthequestionsscientistshavepuzzledover.Perhapstheleastcontroversialassertionaboutthepterosaursisthattheywerereptiles.Theirskulls,pelvises,andhindfeetarereptilia
3、n.Theanatomyoftheirwingssuggeststhattheydidnotevolveintotheclassofbirds.Inpterosaursagreatlyelongatedfourthfingerofeachforelimbsupportedawinglikemembrane.Theotherfingerswereshortandreptilian,withsharpclaws.Inbirdsthesecondfingeristheprincipalstrutofthewing,whichconsistspr
4、imarilyoffeathers.Ifthepterosaurswalkedonallfours,thethreeshortfingersmayhavebeenemployedforgrasping.Whenapterosaurwalkedorremainedstationary,thefourthfinger,andwithitthewing,couldonlyturnupwardinanextendedinvertedVshapealongeachsideoftheanimal’sbody.Thepterosaursresemble
5、dbothbirdsandbatsintheiroverallstructureandproportions.Thisisnotsurprisingbecausethedesignofanyflyingvertebrateissubjecttoaerodynamicconstraints.Boththepterosaursandthebirdshavehollowbones,afeaturethatrepresentsasavingsinweight.Inthebirds,however,thesebonesarereinforcedmo
6、remassivelybyinternalstruts.Althoughscalestypicallycoverreptiles,thepterosaursprobablyhadhairycoats.T.H.Huxleyreasonedthatflyingvertebratesmusthavebeenwarm-bloodedbecauseflyingimpliesahighrateofmetabolism,whichinturnimpliesahighinternaltemperature.Huxleyspeculatedthatacoa
7、tofhairwouldinsulateagainstlossofbodyheatandmightstreamlinethebodytoreducedraginflight.Therecentdiscoveryofapterosaurspecimencoveredinlong,dense,andrelativelythickhairlikefossilmaterialwasthefirstclearevidencethathisreasoningwascorrect.Effortstoexplainhowthepterosaursbeca
8、meairbornehaveledtosuggestionsthattheylaunchedthemselvesbyjumpingfromcliffs,bydroppingfromtrees,
