大学英语四级模拟题十三及答案

大学英语四级模拟题十三及答案大学英语四级模拟题十三及答案PartⅡReadingComprehension(35minutes)Directions:Thereare4passagesinthispart.Eachpassageisfollowedbysomequestionsorunfinishedstatements.ForeachofthemtherearefourchoicesmarkedA),B),C)andD).YoushoulddecideonthebestchoiceandmarkthecorrespondingletterontheAnswerSheetwithasinglelinethroughthecenter.Questions21to25arebasedonthefollowingpassage:Someradiosingalswereheardin1967.Theywerecomingfromapointintheskywheretherewasunknownstar.Theywerecomingveryregularly,too:aboutonceasecond,iftheywerecontrolledbyclock.Thescientistswhoheardthesignalsdidnottellanybodyelse.Theywereratherafraidtotellincasetheyfrightenedpeople.Thesignalswerecomingfromaverysmallbody—nobigger,perhapsthantheearth.Wasthatwhynolightcouldbeseenfromit?Orwerethesignalscomingfromaplanetthatbelongedtosomeotherstar?Therewasnoendtothequestions,butthescientistskeptthenewssecret.“Perhapsthereareintelligentbeingsoutthere.”theythought,“whoaretryingtosendmessagestootherplanets,ortous?Sothenewswasnotgiventothenewspaper.Instead,thescientistsstudiedthesignalsandsearchedforotherslikethem...Well,allthathappenedin1967and1968.Sincethenscientistshavelearntmoreaboutthosestrange,regular,radiosignals.Andtheyhavetoldthestory,ofcourse.Thesignalsdonotcomefromaplanet;theycomefromanewkindofstarcalleda“pulsar””.Aboutahundredotherpulsarshavenowbeenfound,andmostofthemareverylikethefirstone.Pulsarsarestrongradiostars.Theyarethesmallestbuttheheavieststarsweknowatpresent.Ahandfulofpulsarwouldweighafewthousandtons.Theirlight—iftheygivemuchlight—istoosmallforustosee.Butwecanbesureofthis,nointelligentbeingsarelivingonthem.21.Theradiosignalsdiscussedinthispassage____.A.wereregularB.werecontrolledbyaclockC.wereheardin1967onlyD.weresecretmessages22.Theradiosingalsweresentby____.A.asatelliteB.aplanetC.askybodywhichwasunknownatthattimeD.intelligentbeingswhowereunknownatthattime23.Thescientistsdidnottellpeopleaboutthesignalsbecause____.A.thesingalsstoodforsecretmessagesB.peoplewouldaskthemtoomanyquestionsC.theydidnotwanttofrightenpeopleD.theystoodforunimportantmessages24.Apulsaris____.A.asmallheavystarwhichsendsoutstrongradiosignalsandcannotbeseenB.asmallheavyplanetwhichsendsoutstrongradiosignalsandcannotbeseenC.asmallheavysatellitewhichsendsoutstrongradiosignalsandcannotbeseenD.asmallintelligentbeingwhosendsoutstrongradiosignalsandcannotbeseen25.Whichofthefollowingistrue?A.Oneofthepulsarsfoundbyscientistssendsradiosignals.B.Pulsarbegantosendradiosingalsin1967.C.Scientistshavesearchedforpulsarsformanyyearsbutfoundnone.D.Scientistshavefoundmanypulsarssince1967.Questions26to30arebasedonthefollowingpassage:Overvastareasofeverycontinent,therainfallandvegetationnecessaryforlifearedisappearing.Alreadymorethan40percentoftheearth'slandisdesertordesertlike.About628millionpeople—oneoutofseven—liveinthesedryregions.Inthepast,theyhavemanagedtosurvive,butwithdifficulty.[ZZ(Z]Nowlargelythroughproblemscausedbymodernlife,theirexistenceisthreatenedbytheslow,steadyspreadoftheearth'sdeserts.Scientistsstilldonotunderstandallthecomplexproblemsofthedesert,buttherehavebeenmanyideasforsavingtheland.SandiArabiahasplanted10milliontreestohelpkeepthesandfromtakingoverfertileareas.TheIsraelisareagainusingsomeofthewatercollectionsystemsleftbytheancientpeopleintheNegevdesert.Theyplantowatertheirorchardswiththeextrawater.SomeSahelfarmersstillraisecattleontheirpoorfarmland,butbeforethecattlearesold,theyaretakentogreenerlandsinthesouthtogetfat.26.Whatisthearticlemainlyconcerned?A.Theproblemofspreadingdesert.B.Therainfallandvegetationindesertareas.C.Thewatercollectionsystems.D.Thedifferencebetweenmodernlifeandancientlife.27.“oneoutofseven”refersto____.A.morethanathirdofthelands'earthB.thepercentageoftheearth'slandthatisdesert-likeC.thenumberofpeoplewholiveindryregionsD.adayofaweek28.Inparagraph2,“theyaretakentothegreenerlandsinthesouth.”Theyrefersto____.A.theSahelfarmlandB.thefarmersC.thecattlesD.thetrees29.Howmanyideasforsavingthelandaredescribed?A.Five.B.Two.C.Four.D.Three.30.Whichofthefollowingstatementsistrue,accordingtothepassage?A.Theearth'sdesertareslowlyspreading.B.Oneoutof10peoplelivesindryregions.C.Theirlifeinthedesertisthreatenednowbytraditionalproblems.D.NewwaterwellscansolvetheprobleminAfrica'sdesert.Questions31to35arebasedonthefollowingpassage:Telephone,television,radio,andtelegraphallhelppeoplecommunicatewitheachother.Becauseofthesedevices,ideasandnewsofeventsspreadquicklyallovertheworld.Forexample,withinseconds,peoplecanknowtheresultsofanelectioninanothercountry.Aninternationalfootballmatchcomesintothehomesofeveryonewithatelevisionset.Newsofadisastersuchasanearthquakeorafloodcanbringhelpfromdistantcountrieswithinhours,helpisontheway.Becauseofmoderntechnologylikethesatellitesthattravelaroundtheworld,informationtravelsfast.Howhasthisspeedofcommunicationchangedtheworld?Tomanypeople,theworldhasbecomesmaller.Ofcoursethisdoesnotmeanthattheworldisactuallyphysicallysmaller.Itmeansthattheworldseemssmaller.Twohundredyearsago,communicationbetweenthecontinentstookalongtime.Allnewswascarriedonshipst