大学英语四级考试Model Test Three.docx
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大学英语四级考试Model Test Three.docx
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大学英语四级考试ModelTestThree
大学英语四级考试
ModelTestThree
PartⅠWriting
Directions:
Forthispart,youareallowed30minutestowritealetter.Youshouldwriteatleast120wordsfollowingtheoutlinegivenbelowinChinese:
给你的外国朋友写一封信,告诉他(她)你已经被美国的一所大学录取,但你苦恼的是自己的听力和口语水平不够,你想寻求他(她)对于如何提高听和和口语的建议。
PartⅡReadingComprehension(SkimmingandScanning)
Directions:
Inthispart,youwillhave15minutestogooverthepassagequicklyandanswerthequestionsonAnswerSheet1.Forquestions1-7,choosethebestanswerfromthefourchoicesmarked[A],[B],[C]and[D].Forquestions8-10,completetilesentenceswiththeinformationgiveninthepassage.
TheEarth
PowerandLight
Comparedtotherestoftheuniverse,theEarthisverysmall.Ourplanetandeight(ormaybenine)othersorbittheSun,whichisonlyoneofabout200billionstarsinourgalaxy.Ourgalaxy,theMilkyWay,ispartoftheuniverse,whichincludesmillionsofothergalaxiesandtheirstarsandplanets.Bycomparison,theEarthismicroscopic.
Comparedtoaperson,ontheotherhand,theEarthisenormous.Ithasadiameterof7,926miles(12,756kilometers)attheequator,andithasamassofabout6×1024kilograms.TheEarthorbitstheSunataspeedofabout66,638milesperhour(29.79kilometerspersecond).Don'tdwellonthosenumberstoolong,though;toalotofpeople,theEarthisinconceivably,mind-bogglinglybig.Andit'sjustafractionofthesizeoftheSun.
FromourperspectiveonEarth,theSunlooksverysmall.Thisisbecauseit'sabout93millionmilesawayfromus.TheSun'sdiameteratitsequatorisabout100timesbiggerthanEarth's,andaboutamillionEarthscouldfitinsidetheSun.TheSunisinconceivably,mind-bogglinglybigger.
ButwithouttheSun,theEarthcouldnotexist,inasense,theEarthisagiantmachine,fullofmovingpartsandcomplexsystems.Allthosesystemsneedpower,andthatpowercomesfromtheSun.
TheSunisanenormousnuclearpowersource-throughcomplexreactions,ittransformshydrogenintohelium,releasinglightandheat.Becauseofthesereactions,everysquaremeterofourplanet'ssurfacegetsabout342WattsofenergyfromtheSuneveryyear.Thisisabout1.7×1017Wattstotal,orasmuchas1.7billionlargepowerplantscouldgenerate.YoucanlearnabouthowtheSuncreatesenergyinHowtheSunWorks.
WhenthisenergyreachestheEarth,itprovidespowerforavarietyofreactions,cyclesandsystems.Itdrivesthecirculationoftheatmosphereandtheoceans.Itmakesfoodforplants,whichmanypeopleandanimalseat.LifeonEarthcouldnotexistwithouttheSun,andtheplanetitselfwouldnothavedevelopedwithoutit.
Toacasualobserver,theSun'smostvisiblecontributionstolifearelight,heatandweather.
NightandDay
SomeoftheSun'sbiggestimpactsonourplanetarealsoitsmostobvious.AstheEarthspinsonitsaxis,partsoftheplanetareintheSunwhileothersareintheshade.Inotherwords,theSunappearstoriseandset.Thepartsoftheworldthatareindaylightgetwarmerwhilethepartsthataredarkgraduallylosetheheattheyabsorbedduringtheday.
YoucangetasenseofhowmuchtheSunaffectstheEarth'stemperaturebystandingoutsideonapartlycloudyday.WhentheSunisbehindacloud,youfuelnoticeablycoolerthanwhenitisn't.ThesurfaceofourplanetabsorbsthisheatfromtheSunandemitsitthesamewaythatpavementcontinuestogiveoffheatinthesummeraftertheSungoesdown.Ouratmospheredoesthesamethings-itabsorbstheheatthatthegroundemitsandsendssomeofitbacktotheEarth.
TheEarth'srelationshipwiththeSunalsocreatesseasons.TheEarth'saxistipsalittle-about23.5degrees.OnehemispherepointstowardtheSunastheotherpointsaway.ThehemispherethatpointstowardtheSuniswarmerandgetsmorelight--it'ssummerthere,andintheotherhemisphereit'swinter.Thiseffectislessdramaticneartheequatorthanatthepoles,sincetheequatorreceivesaboutthesameamountofsunlightallyear.Thepoles,ontheotherhand,receivenosunlightatallduringtheirwintermonths,whichispartofthereasonwhythey'refrozen.
Mostpeoplearesousedtothedifferencesbetweennightandday(orsummerandwinter)thattheytakethemforgranted.Butthesechangesinlightandtemperaturehaveanenormousimpactonothersystemsonourplanet.Oneisthecirculationofairthroughouratmosphere.Forexample:
TheSunshinesbrightlyovertheequator.TheairgetsverywarmbecausetheequatorfacestheSundirectlyandbecausetheozonelayeristhinnerthere.
Astheairwarms,itbeginstorise,creatingalowpressuresystem.Thehigheritrises,themoretheaircools.Watercondensesastheaircools,creatingcloudsandrainfall.Theairdriesoutastherainfalls.Theresultiswarm,dryair,relativelyhighinouratmosphere.
Becauseofthelowerairpressure,airrushestowardtheequatorfromthenorthandsouth.Asitwarms,itrises,pushingthedryairawaytothenorthandthesouth.
Thedryairsinksasitcools,creatinghigh-pressureareasanddesertstothenorthandsouthoftheequator.
ThisisjustonepieceofhowtheSuncirculatesairaroundtheworld--oceancurrents,weatherpatternsandotherfactorsalsoplayapart.Butingeneral,airmovesfromhigh-pressuretolow-pressureareas,muchthewaythathigh-pressureairrushesfromthemouthofaninflatedballoonwhenyouletgo.Heatalsogenerallymovesfromthewarmerequatortothecoolerpoles.Imagineawarmdrinksittingonyourdesk--theairaroundthedrinkgetswarmerasthedrinkgetscolder.ThishappensonEarthonanenormousscale.
TheCoriolisEffect,aproductoftheEarth'srotation,affectsthissystemaswell.Itcauseslargeweathersystems,likehurricanes,torotate.Ithelpscreatewestward-runningtradewindsneartheequatorandeastward-runningjetstreamsinthenorthernandsouthernhemispheres.Thesewindpatternsmovemoistureandairfromoneplacetoanother,creatingweatherpatterns.(TheCoriolisEffectworksonalargescale--itdoesn'treallyaffectthewaterdrainingfromthesinklikesomepeoplesuppose.)
TheSungetsmuchofthecreditforcreatingbothwindandrain.WhentheSunwarmsairinaspecificlocation,thatairrises,creatinganareaoflowpressure.Moreairrushesinfromsurroundingareastofillthevoid,creatingwind.WithouttheSun,therewouldn'tbewind.Therealsomightnotbebreathableairatall.
WaterandFire
TheSunhasahugeeffectonourwater.Itwarmstheoceansaroundthetropics,anditsabsencecoolsthewateraroundthepoles.Becauseofthis,oceancurrentsmovelargeamountsofwarmandcoldwater,drasticallyaffectingtheweatherandclimatearoundtheworld.TheSunalsodrivesthewatercycle,whichmovesabout18,757cubicmiles(495,000cubickilometers)ofwatervaporthroughtheatmosphereeveryyear.
Ifyou'veevergottenoutofaswimmingpoolonahotdayandrealizedafewminuteslaterthatyouweredryagain,youhavefirsthandexperiencewithevaporation.Ifyou'veseenwaterformonthesideofacolddrink,you'veseencondensationinaction.Theseareprimarycomponentsofthewatercycle,alsocalledthehydrologiccycle,whichexchangesmoisturebetweenbodiesofwaterandlandmasses.Thewatercycleisresponsibleforcloudsandrainaswellasoursupplyofdrinkingwater.
1.HowmanyEarthscouldfitinsidetheSun?
[A]Onemillion.
[B]93million.
[C]Twomillion.
[D]100million.
2.Earthwouldnothavedevelopedwithout______.
[A]water
[B]fertilizer
[C]soil
[D]theSun
3.Whatdoesouratmospheredo?
[A]ItabsorbstheheatfromthegroundandsendsittotheSun.
[B]ItabsorbstheheatfromtheSunandemitsitbacktotheEarth.
[C]ItabsorbstheheatfromtheSunandemitsitthesameway.
[D]ItabsorbstheheatthegroundemitsandsendssomeofitbacktotheEarth.
4.______receivesaboutthesameamountofsunlightallyear.
[A]Thepoles
[B]Theequator
[C]Thenorthtemperatezone
[D]Thesouthtemperatezone
5.Airrushestowardtheequatorfromthenorthandsouth______.
[A]becauseofthedryair
[B]becauseofthecoolair
[C]becauseofthelowerairpressure
[D]becauseofthehigherairpressure
6.Whatdoesn'ttheCoriolisEffectcause?
[A]Westward-runningtradewinds.
[B]Hurricanes.
[C]Thewaterdrainingfromthesink.
[D]Eastward-runningjetstreams.
7.TheSunhascloselyrelationtocreate______.
[A]wind
[B]theair
[C]soil
[D]fire
8.TheSunhasahugeeffecton______.
9.Ifyou'veseenwaterformonthesideofacolddrink,you'veseen______.
10.Thewatercycleisresponsibleforclouds,rainand______.
PartⅢListeningComprehension
SectionA
Directions:
Inthissection,youwillhear8shortconversationsand2longconversations.Attheendofeachconversation,oneormorequestionswillbeaskedaboutwhatwassaid.Boththeconversationandthequestionswillbespokenonlyonce.Aftereachquestiontherewillbeapause.Duringthepause,youmustreadthefourchoicesmarked[A],[B],[C]and[D],anddecidewhichisthebestanswer.ThenmarkthecorrespondingletteronAnswerSheet2withasinglelinethroughthecentre.
Questions11to18arebasedontheconversationyouhavejustheard.
11.[A]Atthedepartmentstore.
[B]Attheoffice.
[C]Intherestaurant.
[D]Inthedrugstore.
12.[A]Themanshouldn'texpecthertogoalong.
[B]Shedoesn'tthinkshehasenoughmoney.
[C]She'llgoeventhoughthemovieisbad.
[D]Themanshouldcountthenumberofpeoplegoing;
13.[A]Shewasn'treallystudying.
[B]Shehadn'tfinishedwritingherarticles.
[C]Shehadfurnishedherhouse.
[D]She
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