小学、初中、高中各种试卷真题知识归纳文案合同PPT等免费下载www.doc985.com小学、初中、高中各种试卷真题知识归纳文案合同PPT等免费下载www.doc985.com人教（2019）版高中英语选择性必修第一册第二单元限时练时间：100分钟分值：120第一部分阅读理解(共两节，满分50分)第一节(共15小题；每小题2.5分，满分37.5分)阅读下列短文，从每题所给的A、B、C和D四个选项中，选出最佳选项，并在答题纸上将该项涂黑AUnsolvedMysteriesAboutthePlanetEarthMystery1:Wheredidwatercomefrom?Watercoversmorethan70percentoftheEarth'ssurfaceandthatmakestheEarthearnthenickname"theblueplanet".Thenwherediwatercomefrom?ThemostpopularscientifictheorystatesthattheH2camefromseveralviolentasteroids(小行星）coveredwithice.AnothesuggeststhatthewateractuallyhasbeenaroundsincetheEarth'sformationHoweverithappened,though,it'scertainlyworkedoutwellfortheEarthlifeforms.Mystery2:Whataboutalltheoxygen?Anotherthingistheplanet'soxygen.Tinycreaturesreleasedoxygenasawasteproduct,fillingtheatmospherewithit.Afterthat,thelevelofoxygeintheEarth'satmospherewentwildlyupanddownuntilitfinallycalmedownaround540millionyearsago.Sincethen,it'sremainedataboutthebreathablelevelweknowtoday.Butwhatcausedittobesuddenlysteady?·Mystery3:WhatcausedtheCambrian(寒武纪）Explosion?TheCambrianExplosionreferstotheexplosionofcomplexlifeformsthatoccurredonEarthabout540millionyearsago.Beforethen,lifehadconsistedmostlyofmicrobes.ButatthebeginningoftheCambrianperiodcomplexcreaturesbegandevelopingatarateneverseenbefore.Suddenly,lifeformshadbrains,eyes,andbones.MostlivingcreaturestodaycantracetheirbloodbacktotheCambrianperiod.Mystery4:Willwebeabletopredictearthquakes?Westillhaven'tbeenabletocomeupwithawaytoaccuratelypredictearthquakes.Wecancertainlytry,butourcurrenttechnologycannotpredictthemexactly.Weknowthatearthquakesstartwhentherockcracksundergroundandtheenormousenergyreleasedintheprocesscausesvibration,whichgeneratesearthquakewaves,butwehaven'tfiguredoutwhythathappens,orhowtopredictit.1.WhatwascreatedbycreaturesonEarth?A.Water.B.Bacterium.C.Oxygen.D.Ice.小学、初中、高中各种试卷真题知识归纳文案合同PPT等免费下载www.doc985.com小学、初中、高中各种试卷真题知识归纳文案合同PPT等免费下载www.doc985.com2.WhichofthefollowingtalksabouttheEarth'sadvancedspecies?A.Mystery1.B.Mystery2.C.Mystery4.D.Mystery3.3.WhatdoweknowaboutMystery4?A.Itisamatterthathasextremelypracticalsignificance.B.Itwillbesolvedinthenearfuture.C.Itisthemostdifficultmysterytosolveofthefour.D.Itistheoldestmysteryofthefour.BRussFeewasasleepinsidehistentlastsummerinCanada'sBanffNationalParkwhenscreamsshockedandawokehim.Throwingonhisshoesandgrabbingalanternhiswifehadhandedtohim,heranouttoinvestigate.Despitethedarkness,hecouldmakeoutaneighboringtent.Therewasawolfdraggingsomethinginhisteeth-aman.Momentsearlier,ElisaandMatt,wereasleepwiththeirtwoyoungchildrenwhenthewolftoreintotheirtent."Itwaslikesomethingoutofahorrormovie,"Elisarecalled.Forthreeminutes,MattthrewhisbodyinfrontofElisaandtheboysandfoughtagainstthewolf.Atonepoint,Mattgottheupperhand,butthewolfturnedthetablesanddraggedMattoutsidewhileElisawaspullingonhislegstryingtogethimback.ItwasthenthatRussFeeenteredthepicture.Herantowardthebeast,kickingitinthehip.ThewolfdroppedMattandemergedfromthetent.Feefeltlikehehadhitsomeonebiggerthanhim.BeforethewolfcouldturnitsangeratFee,Matt,whosearmswerebloody,restartedthebattle.Thementhrewrocksatthewolf,keepingitoff.Thenthefamiliesf...