EXTINCTIONOFDINOSAURS恐龍的滅絕EXTINCTIONOFParagraph1

Paleontologistshavearguedforalongtimethatthedemiseofthedinosaurswascausedbyclimaticalterationsassociatedwithslowchangesinthepositionsofcontinentsandseasresultingfromplatetectonics.OffandonthroughouttheCretaceous(thelastperiodoftheMesozoicera,duringwhichdinosaursflourished),largeshallowseascoveredextensiveareasofthecontinents.Datafromdiversesources,includinggeochemicalevidencepreservedinseafloorsediments,indicatethattheLateCretaceousclimatewasmilderthantoday’s.Thedayswerenottoohot,northenightstoocold.Thesummerswerenottoowarm,northewinterstoofrigid.Theshallowseasonthecontinentsprobablybufferedthetemperatureofthenearbyair,keepingitrelativelyconstant.Paragraph1PaleontologistshParagraph11.Accordingtoparagraph1,whichofthefollowingistrueoftheLateCretaceousclimate?A.Summerswereverywarmandwinterswereverycold.B.Shallowseasonthecontinentscausedfrequenttemperaturechanges.C.Theclimatewasverysimilartotoday’sclimate.D.Theclimatedidnotchangedramaticallyfromseasontoseason.Paragraph11.AccordingtoparParagraph2AttheendoftheCretaceous,thegeologicalrecordshowsthattheseseawaysretreatedfromthecontinentsbackintothemajoroceanbasins.Nooneknowswhy.Overaperiodofabout100,000years,whiletheseaspulledback,climatesaroundtheworldbecamedramaticallymoreextreme:warmerdays,coolernights;hottersummers,colderwinters.Perhapsdinosaurscouldnottoleratetheseextremetemperaturechangesandbecameextinct.Paragraph2AttheendoftheParagraph22.Whichofthefollowingreasonsissuggestedinparagraph2fortheextinctionofthedinosaurs?A.ChangesinthelengthsofthedaysandnightsduringthelateCretaceousperiodB.DroughtscausedbythemovementofseawaysbackintotheoceansC.ThechangefrommildtosevereclimatesduringtheLateCretaceousperiodD.Anextremedecreaseintheaverageyearlytemperatureover10,oooyearsParagraph22.WhichofthefoParagraph3

Iftrue,though,whydidcold-bloodedanimalssuchassnakes,lizards,turtles,andcrocodilessurvivethefreezingwintersandtorridsummers?Theseanimalsareatthemercyoftheclimatetomaintainalivablebodytemperature.It’shardtounderstandwhytheywouldnotbeaffected,whereasdinosaurswerelefttoocrippledtocope,especiallyif,assomescientistsbelieve,dinosaurswerewarm-blooded.CriticsalsopointoutthattheshallowseawayshadretreatedfromandadvancedonthecontinentsnumeroustimesduringtheMesozoic,sowhydidthedinosaurssurvivetheclimaticchangesassociatedwiththeearlierfluctuationsbutnotwiththisone?Althoughinitiallyappealing,thehypothesisofasimpleclimaticchangerelatedtosealevelsisinsufficienttoexplainallthedata.Paragraph3Iftrue,though,Paragraph33.Whydoestheauthormentionthesurvivalof“snakes,lizards,turtles,andcrocodiles”inparagraph3?A.Toarguethatdinosaursmayhavebecomeextinctbecausetheywerenotcold-bloodedanimalsB.ToquestiontheadequacyofthehypothesisthatclimaticchangerelatedtosealevelscausedtheextinctionofthedinosaursC.TopresentexamplesofanimalsthatcouldmaintainalivablebodytemperaturemoreeasilythandinosaursD.TosupportahypothesisthattheseanimalswerenotassensitivetoclimatechangesintheCretaceousperiodastheyaretodayParagraph34.Theword“cope”inthepassageisclosestinmeaningtoA.adaptB.moveC.continueD.competeParagraph3Paragraph35.Accordingtoparagraph3,whichofthefollowingistrueofchangesinclimatebeforetheCretaceousperiodandtheeffectofthesechangesondinosaurs?A.ClimatechangesassociatedwiththemovementofseawaysbeforetheCretaceousperioddidnotcausedinosaurstobecomeextinct.B.ChangesinclimatebeforetheCretaceousperiodcausedseverefluctuationsinsealevel,resultingintheextinctionofthedinosaurs.C.FrequentchangesinclimatebeforetheCretaceousperiodmadedinosaursbetterabletomaintainalivablebodytemperature.D.BeforetheCretaceousperiodtherewerefewchangesinclimate,anddinosaursflourished.Paragraph35.Accordingtoparagraph3,w6.Theword“fluctuations”inthepassageisclosestinmeaningtoA.extremesB.retreatsC.periodsD.variationsParagraph3Paragraph3Paragraph4Dissatisfactionwithconventionalexplanationsfordinosaurextinctionsledtoasurprisingobservationthat,inturn,hassuggestedanewhypothesis.ManyplantsandanimalsdisappearabruptlyfromthefossilrecordasonemovesfromlayersofrockdocumentingtheendoftheCretaceousupintorocksrepresentingthebeginningoftheCenozoic(theeraaftertheMesozoic).BetweenthelastlayerofCretaceousrockandthefirstlayerofCenozoicrock,thereisoftenathinlayerofclay.Scientistsfeltthattheycouldgetanideaofhowlongtheextinctionstookbydetermininghowlongittooktodepositthisonecentimeterofclayandtheythoughttheycoulddeterminethetimeittooktodeposittheclaybydeterminingtheamountoftheelementiridium(lr)itcontained.Paragraph4Dissatisfactionwit7.Whichofthesentencesbelowbestexpressestheessentialinformationinthehighlightedsentenceinthepassage?Incorrectchoiceschangethemeaninginimportantwaysorleaveoutessentialinformation.A.ThefossilrecordsuggeststhattherewasanabruptextinctionofmanyplantsandanimalsattheendoftheMesozoicera.B.FewfossilsoftheMesozoicerahavesurvivedintherocksthatmarktheendoftheCretaceous.C.FossilsfromtheCretaceousperiodoftheMesozoicuptothebeginningoftheCenozoicerahavebeenremovedfromthelayersofrockthatsurroundedthem.D.PlantsandanimalsfromtheMesozoicerawereunabletosurviveintheCenozoicera.Paragraph47.Whichofthesentencesbelo8.Inparagraph4,allthefollowingquestionsareansweredEXCEPT:A.WhyistherealayerofclaybetweentherocksoftheCretaceousandCenozoic?B.WhywerescientistsinterestedindetermininghowlongittooktodepositthelayerofclayattheendoftheCretaceous?C.Whatwastheeffectofthesurprisingobservationscientistsmade?D.WhydidscientistswantmoreinformationaboutthedinosaurextinctionsattheendoftheCretaceous?Paragraph48.Inparagraph4,allthefolParagraph5IthasnotbeencommonatEarth’ssincetheverybeginningoftheplanet’shistory.Becauseitusuallyexistsinametallicstate,itwaspreferentiallyincorporatedinEarth’scoreastheplanetcooledandconsolidated.lrisfoundinhighconcentrationsinsomemeteorites,inwhichthesolarsystem’soriginalchemicalcompositionispreserved.Eventoday,microscopicmeteoritescontinuallybombardEarth,fallingonbothlandandsea.BymeasuringhowmanyofthesemeteoritesfalltoEarthoveragivenperiodoftime,scientistscanestimatehowlongitmighthavetakentodeposittheobservedamountoflrintheboundaryclay.■Thesecalculationssuggestthataperiodofaboutonemillionyearswouldhavebeenrequired.■However,otherreliableevidencesuggeststhatthedepositionoftheboundaryclaycouldnothavetakenonemillionyears.■Sotheunusuallyhighconcentrationoflrseemstorequireaspecialexplanation.■Paragraph5IthasnotbeencoParagraph59.Theword“bombard”inthepassageisclosestinmeaningtoA.approachB.strikeC.passD.circleParagraph59.Theword“bombaParagraph510.Paragraph5impliesthataspecialexplanationoflrintheboundaryclayisneededbecauseA.thelrinmicroscopicmeteoritesreachingEarthduringtheCretaceousperiodwouldhavebeenincorporatedintoEarth’scoreB.thelrintheboundaryclaywasdepositedmuchmorethanamillionyearsagoC.theconcentrationoflrintheboundaryclayishigherthaninmicroscopicmeteoritesD.theamountoflrintheboundaryclayistoogreattohavecomefrommicroscopicmeteoritesduringthetimetheboundaryclaywasdepositedParagraph510.Paragraph5im13.Lookatthefoursquares[■]thatindicatewherethefollowingsentencecouldbeaddedtothepassage.

Consequently,theideathatthelrintheboundaryclaycamefrommicroscopicmeteoritescannotbeaccepted.Wherewouldthesentencebestfit?13.Lookatthefoursquares[Paragraph6Inviewofthesefacts,scientistshypothesizedthatasinglelargeasteroid,about10to15kilometersacross,collidedwithEarth,andtheresultingfalloutcreatedtheboundaryclay.Theircalculationsshowthattheimpactkickedupadustcloudthatcutoffsunlightforseveralmonths,inhibitingphotosynthesisinplants;decreasedsurfacetemperaturesoncontinentstobelowfreezing;causedextremeepisodesofacidrain;andsignificantlyraisedlong-termglobaltemperaturesthroughthegreenhouseeffect.Thisdisruptionoffoodchainandclimatewouldhaveeradicatedthedinosaursandotherorganismsinlessthanfiftyyears.Paragraph6InviewofthesefaParagraph611.Theword“disruption”inthepassageisclosestinmeaningtoA.exhaustionB.disturbanceC.modificationD.disappearanceParagraph611.Theword“disruParagraph6

12.Paragraph6mentionsallofthefollowingeffectsofthehypothesizedasteroidcollisionEXCEPTA.alargedustcloudthatblockedsunlightB.animmediatedropinthesurfacetemperaturesofthecontinentsC.anextremedecreaseinrainfallonthecontinentsD.along-