安徽省六安第一中学2023-2024学年高二下学期期中考试英语试题.pdf

安徽省六安第一中学2023-2024学年高二下学期期中考试英语

试题

学校:___________姓名：___________班级：___________考号：___________

一、阅读理解

UnsolvedMysteriesAbouttheEarth

◆Mystery1:Wheredidallthewatercomefrom?

Watercovers70percentoftheearth’ssurfaceandearnsitthenickname“theblueplanet”.

Andwherediditcomefrom?ThemostpopularscientifictheorystatesthattheHOarrivedinthe

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formofseveralviolentasteroids(小行星)filledwithice.Anothersuggeststhatthewateractually

hasbeenaroundsincetheearth’sformation.Howeverithappened,though,it’scertainlyworked

outwellfortheearth’slifeforms.

◆Mystery2:Whataboutalltheoxygen?

Anotherthingistheplanet’soxygen.Tinycreaturesreleasedoxygenasawasteproduct,

fillingtheatmospherewithit.Afterthat,thelevelofoxygenintheearth’satmospherewentwildly

upanddownuntilitfinallycalmeddownaround540millionyearsago.Sincethen,it’sremained

ataboutthebreathablelevelweexperiencetoday.Butwhatcausedittobesuddenlysteady?

◆Mystery3:WhatcausedtheCambrian(寒武纪)Explosion?

TheCambrianExplosionreferstotheexplosionofcomplexlifethatoccurredontheearth

about540millionyearsago.Beforethen,lifehadconsistedmostlyofbacteria.Butatthe

beginningoftheCambrianperiod,complexcreaturesbegandevelopingatarateneverbefore

seen.Suddenly,advancedlifeformshadbrainseyesandbones.Mostcreaturesalivetodaycan

tracetheirbloodbacktotheCambrianperiod.

◆Mystery4:Willweeverbeabletopredictearthquakes?

Westillhaven’tbeenabletocomeupwithawaytoaccuratelypredictearthquakes,which

ispracticallysignificant.Wecancertain