2019年高考英语一轮总复习 Unit 2 The United Kingdom课时作业 新人教版必修5

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1、2019年高考英语一轮总复习Unit2TheUnitedKingdom课时作业新人教版必修5Ⅰ.阅读理解A(xx·江苏卷)Ifadiversurfacestooquickly，hemaysufferthebends.Nitrogen(氮)dissolved(溶解)inhisbloodissuddenlyliberatedbythereductionofpressure.Theconsequence，ifthebubbles(气泡)accumulateinajoint，issharppainandabentbody—thusthename.Ifthebubblesforminh

2、islungsorhisbrain，theconsequencecanbedeath.Otherair－breathinganimalsalsosufferthisdepression(减压)sicknessiftheysurfacetoofast：whales，forexample.Andsolongago，didichthyosaurs.Thattheseancientseaanimalsgotthebendscanbeseenfromtheirbones.Ifbubblesofnitrogenforminsidethebonetheycancutoffitsbloods

3、upply.Thiskillsthecellsinthebone，andconsequentlyweakensit，sometimestothepointofcollapse.Fossil(化石)bonesthathavecavedinonthemselvesarethusasignthattheanimaloncehadthebends.BruceRothschildoftheUniversityofKansasknewallthiswhenhebeganastudyofichthyosaurbonestofindouthowwidespreadtheproblemwasi

4、nthepast.Whatheparticularlywantedtoinvestigatewashowichthyosaursadaptedtotheproblemofdepressionoverthe150millionyears.Tothisend，heandhiscolleaguestraveledtheworld'snaturalhistorymuseums，lookingathundredsofichthyosaursfromtheTriassicperiodandfromthelaterJurassicandCretaceousperiods.Whenhesta

5、rted，heassumedthatsignsofthebendswouldberarerinyoungerfossils，reflectingtheirgradualevolutionofmeasurestodealwithdepression.Instead，hewasastonishedtodiscovertheopposite.Morethan15%ofJurassicandCretaceousichthyosaurshadsufferedthebendsbeforetheydied，butnotasingleTriassicspecimen(标本)showedevi

6、denceofthatsortofinjury.Ifichthyosaursdidevolveananti－depressionmeans，theyclearlydidsoquickly—and，moststrangely，theylostitafterwards.ButthatisnotwhatDrRothschildthinkshappened.Hesuspectsitwasevolutioninotheranimalsthatcausedthechange.Whalesthatsufferthebendsoftendosobecausetheyhavesurfacedt

7、oescapeapredator(捕食动物)suchasalargeshark.OneofthefeaturesofJurassicoceanswasanabundanceoflargesharksandcrocodiles，bothofwhichwerefondofichthyosaurlunches.Triassicoceans，bycontrast，weremercifullyshark－andcrocodile－free.IntheTriassic，then，ichthyosaurswereto