2023年下半年公共英語四級(jí)專題模擬訓(xùn)練

第頁共頁2023年下半年公共英語四級(jí)專題模擬訓(xùn)練更多精彩內(nèi)容請及時(shí)____應(yīng)屆畢業(yè)生考試網(wǎng)!ReadingComprehensionpartAReadthefollowingtwotexts.AnswerthequestionsbeloweachtextbychoosingA.B.CorD.WhenwasheliumintheUniversityformed?Theelementsotherthanhydrogenandheliumexistinsuchsmallquantitiesthatitisaccuratetosaythattheuniverseissomewhatmorethan75percenthydrogen.Astronomershavemeasuredtheabundanceofheliumthroughoutourgalaxyandinothergalaxiesaswell.Heliumhasbeenfoundinoldstars,inrelativelyyoungones,ininterstellargas,andinthedistantobjectsknownasqua____.Heliumnucleihavealsobeenfoundtobeconstituentsofcosmicraysthatfallontheearth(cosmic“rays”arenotreallyaformofradiation;theyconsistofrapidlymovingparticlesofnumerousdifferentkinds).Itdoesn’tseemtomakeverymuchdifferencewheretheheliumisfound.Itsrelativeabundanceneverseemstovarymuch.Insomeplaces,theremaybeslightlymoreofit;inothers,slightlyless,buttheratioofheliumtohydrogennucleialwaysremainsaboutthesame.Heliumiscreatedinstars.Infact,nuclearreactionsthatconverthydrogentoheliumareresponsibleformostoftheenergythatstarsproduce.However,theamountofheliumthatcouldhavebeenproducedinthismannercanbecalculated,anditturnsouttobenomorethanafewpercent.Theuniversehasnotexistedlongenoughforthisfiguretobesignificantlygreater.Consequently,iftheuniverseissomewhatmorethan25percentheliumnow,thenitmusthavebeenabout25percentheliumatatimenearthebeginning.However,whentheuniversewaslessthanoneminuteold,noheliumcouldhaveexisted.Calculationsindicatethatbeforethistimetemperaturesweretoohighandparticlesofmaterweremovingaroundmuchtoorapidly.Itwasonlyaftertheone-minutepointthatheliumcouldexist.Bythistime,theuniversehadcooledsufficientlythatneutronsandprotonscouldsticktogether.Butthenuclearreactionsthatledtotheformationofheliumwentonforonlyarelativelyshorttime.Bythetimetheuniversewasafewminutesold,heliumproductionhadeffectivelyceased.1.Whatdoesthepassagemainlyexplain?A.Howstarsproduceenergy.B.Thedifferencebetweenheliumandhydrogen.C.Whenmostoftheheliumintheuniversehydrogen.D.Whyhydrogenisabundant.2.Accordingtothepassage,heliumis____.A.thesecond-mostabundantelementintheuniverseB.difficulttodetectC.theoldestelementintheuniverseD.themostprevalentelementinqua____3.Whydoestheauthormention“cosmicrays”inparagraph2?A.aspartofalistofthingscontaininghelium.B.Asanexleofanunsolvedastronomicalpuzzle.C.Toexplainhowtheuniversebegan.D.Toexplaintheabundanceofhydrogenintheuniverse.4.Thecreationofheliumwithinstars____.A.cannotbemeasuredB.producesenergyC.producesheliumtobemuchmoreabundantinoldstarsthaninyoungstars.5.Mostoftheheliumintheuniversewasformed_____.A.ininterstellarspaceB.inaveryshorttimeC.duringthefirstminuteoftheuniverse’sexistenceD.beforemostofthehydrogen解析：1.C本文的題目是WhenwasheliumintheUniversityformed?根據(jù)題目并結(jié)合文章的內(nèi)容，我們可以判斷，本文主要介紹的是氦元素是何時(shí)在宇宙中形成的。2.A在第一段中我們知道：宇宙中除了氫和氦的數(shù)量比擬多之外，其它元素的數(shù)量都很少。而且，氫在宇宙元素總量中占75%，所以氦元素在宇宙中一定是占第二位，僅次于氦。3.A文章第二段中介紹了許多包含氦的物質(zhì)，包括inoldstars,inrelativelyyoungones,ininterstellargas,andinthedistantobjectsknownasqua____同時(shí)作者還提到了宇宙射線，并告訴我們宇宙射線中也包含氦。因此，作者在這里也提到了cosmicrays的目的是要使人們知道另外一種包含氦的物質(zhì)，詳細(xì)而言，就是說宇宙射線也是眾多包含氦元素的物質(zhì)中的一局部。4.B第三段開頭有這樣一句話：Infact,nuclearreactionsthatconverthydrogentoheliumareresponsibleformostoftheenergythatstarsproduce.這句話的意思是，星體產(chǎn)生的多數(shù)能量來與巴氫轉(zhuǎn)變?yōu)楹さ脑雍朔错憽Ｒ簿褪钦f，星體上的氫轉(zhuǎn)變?yōu)楹さ脑雍朔错懏a(chǎn)生了能量，這與選項(xiàng)A中的`“星體中的氦的創(chuàng)造過程中產(chǎn)生了能量”是一致的。5.B文章的末尾有這樣一句話：Butthenuclearreactionsthatledtotheformationofheliumwe