2019年高考英语一轮巩固达标练题Unit3Underthesea含解析新人教版.doc

2019年高考英语一轮巩固达标练题Unit3Underthesea含解析新人教版.doc

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时间:2020-03-08

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1、Underthesea***阅读理解。OldFossilsScientistshavefoundwhattheythinkisprobablytheoldestfossilonEarth,aremnantoflifefrom3.7billionyearsagowhenEarth’sskieswereorangeanditsoceansgreen.InanewlymeltedpartofGreenland,Australianscientistsfoundtheleftoverstructurefromacommunityofmi

2、crobes(微生物)thatlivedonanancientseafloor.Basedontheiranalysisofthefossils,theresearchersdeterminedthattheyare220millionyearsolderthanthosediscoveredinWesternAustralia,whichwere3.48billionyearsold.Thediscoveryshowslifemayhaveformedquickerandmoreeasilythanoncethought,ab

3、outhalfabillionyearsafterEarthformed.Andthatmayalsogivehopeforlifeformingelsewhere,suchasMars,saidstudyco-authorMartinVanKranendonkoftheUniversityofNewSouthWalesanddirectoroftheAustralianCenterforAstrobiology."Itgivesusanideahowourplanetevolvedandhowlifegainedafootho

4、ld,"VanKranendonksaid.ScientistshadthoughtitwouldtakeatleasthalfabillionyearsforlifetoformafterthemoltenEarthstartedtocoolabit,butthisshowsitcouldhavehappenedquicker,hesaid.That’sbecausethenewlyfoundfossilisfartoocomplextohavedevelopedsoonaftertheplanet’sfirstlifefor

5、ms,hesaid.Inanoutcropofrocksthatusedtobecoveredwithiceandsnowwhichmeltedafteranexceptionallywarmspring,theAustralianteamfoundstromatolites(叠层石),whicharelayeredstructuresthatareoftenproducedbyacommunityofmicrobes.Thestromatoliteswereabout1to4centimetershigh."Itisliket

6、hehouseleftbehindmadebythemicrobes,"VanKranendonksaid."Scientistsusedthelayersofashfromvolcanoesandtinyzircon(锆石)withuraniumandestimatedthattheydatebackto3.7billionyearsago."Thedatingseemsaboutright,saidAbigailAllwood,aNASAastrobiologistwhofoundthepreviousoldestfossi

7、l,from3.48billionyearsago,inAustralia.ButAllwoodsaidshe9isnotcompletelyconvincedthatwhatVanKranendonk’steamfoundoncewasalive.Shesaidtheevidencewasn’tconclusiveenoughthatitwaslifeandnotageologicquirk(地质巧合)."Itwouldbenicetohavemoreevidence,butintheserocksthat’salottoas

8、k,"Allwoodsaidinanemail.1.Theunderlinedwords"gainedafoothold"inParagraph3mean______.A.continuedB.changedC.increasedD.Started2.Wecan

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