大学六级模拟544.docx

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大学六级模拟544.docx

大学六级模拟544

ModelTestOne

PartIWriting(30minutes)

Directions:

Forthispart,youareallowed30minutestowriteashortessayentitledDoCollegeStudentsNeedCareerOrientation?

Youshouldwriteatleast150wordsfollowingtheoutlinegivenbelow:

1.许多大学生缺乏明确的职业规划

2.职业规划的重要性

3.我的看法

DoCollegeStudentsNeedCareerOrientation?

PartⅡReadingComprehension(SkimmingandScanning)(15minutes)

Directions:

Inthispart,youwillhave15minutestogooverthepassagequicklyandanswerthequestionsonAnswerSheet1.Forquestions1-7,choosethebestanswerfromthefourchoicesmarkedA),B),C)andD).Forquestions8-10,completethesentenceswiththeinformationgiveninthepassage.

EarthWillSurviveGlobalWarming,ButWillWe?

Thenotionthathumanactivity,ortheactivityofanyorganism,canaffectEarthonaplanetaryscaleisstillahardoneformanypeopletoswallow.Anditisthiskindofdisbeliefthatfuelsmuchofthepublicskepticismsurroundingglobalwarming.

ApollconductedlastsummerbythePewResearchCenterfoundthatonly41percentofAmericansbelievetheburningoffossilfuelscausesglobalwarming.ButinameetingthisweekinParis,officialsfrom113nationshaveagreedthatahighlyanticipatedinternationalreportwillstatethatglobalwarmingwas"verylikely"causedbyhumanactivity.Theideathatbiologycanaltertheplanetinbroadanddramaticwaysiswidelyacceptedamongscientists,andtheypointtoseveralprecedentsthroughoutthehistoryoflife.

Themightymicrobes

Human-causedglobalwarming--alsocalled"anthropogenic"globalwarming--isthelatestexampleoflifealteringEarth,butitisnotthemostdramatic.

ThattitleprobablygoestotheoxygenationofEarth'searlyatmospherebyancientmicrobesastheybegantoharnessthepowerofsunlightthroughphotosynthesis(光合作用).

Humans"arehavingastrongeffectonglobalgeochemicalcycles,butitdoesnotcompareatalltotheadventofoxygenicphotosynthesis,"saidKatrinaEdwards,ageo-microbiologistattheUniversityofSouthernCalifornia(USC)."Thatwasacatastrophicenvironmentalchangethatoccurredbefore2.2billionyearsagowhichwreakeditsfullwrathontheEarthsystem."

Edwardsstudiesanotherwaylifeimpactstheplanetinlargelyunseenways.Shefocusesonhowmicrobeslivingonthedarkoceanfloortransformmineralsthroughakindofunderwaterpower.

"Thesemicrobesarecompletelyoffradarintermsofglobalbiogeochemicalcycles,"EdwardstoldLive-Science."Wedon'tconsiderthemaspartoftheEarthsystemrightnowinourcalculationaboutwhat'sgoingon,andwedon'tconsiderthemintermsofhowtheEarthsystemwillmoveforwardintothefuture."

Thesereactionsarestronglyinfluencedbylifeandhavebeenoccurringforbillionsofyears,foraslongastheoceanshavebeenoxygenatedandtherehavebeenmicrobesinhabitingtheseafloor,Edwardssaid.

CreatingEarth

Onland,microbes,andinparticularaformofbacteriacalledcyanobacteria(固氮蓝藻),helpkeepsoilinplaceandsuppressdust.

"We'dcertainlyhavemoreduststormsanditwouldnotbeanywhereasniceonEarthiftheyweren'taround,"saidJayneBelnap,aresearcherwiththeUnitedStatesGeologicalSurvey.

Scientistsbelievethetinylife-formsperformedthesamerolesonearlyEarth."Oneofthebigproblemsforgeologistsisthat,OK,youhavethisbigballofrock,thesoilisweatheringoutandyouhavetheseferociouswinds.Whatintheworldisholdingthesoilinplaceasitweathersoutoftherocks?

"Belnapsaidinatelephoneinterview."Cyanobacteriaarealsocreditedwiththatfunction."

Themicrobesanchoredsoiltotheground;thiscreatedhabitatsforlandplantstoevolveandeventuallyforustoevolve."TheyliterallycreatedEarthinasense,"Belnapsaid.

"Cyanobacteriaarejustlike'it',"shecontinued."I'vebeentellingeverybodytomakeasmallaltarandoffersacrificeseverynight.Weowethemeverything."

Asnowballplanet

Themightymicrobesalsotriggeredsuddenclimaticshiftssimilartowhathumansaredoingnow.Recentstudiessuggestthattheproliferationofcyanobacteria2.3billionyearsagoledtoasuddeniceageandthecreationofa"SnowballEarth."

Astheycarryoutphotosynthesis,cyanobacteriabreakapartwaterandreleaseoxygenasawasteproduct.Oxygenisoneofthemostreactiveelementsaround,anditsreleaseintotheatmosphereinlargeamountsdestroyedmethane(沼气),agreenhousegasthatabsorbedthesun'senergyandhelpedkeepourplanetwarm.

SomescientiststhinkthedisappearanceofthismethaneblanketplungedtheplanetintoacoldspellsoseverethatEarth'sequatorwascoveredbyamile-thicklayerofice.

Earthmightstillbefrozentodayifnotfortheappearanceofnewlifeforms.Asorganismsevolved,manydevelopedtheabilitytobreatheoxygen.Intheprocess,theyexhaledanothergreenhousegas,Carbondioxide,whicheventuallyice-outtheworld.Thatwasthefirstbiologicallytriggerediceage,butothersfollowed,saidRichardKopp,aCaltechresearcherwhohelpedpiecetogethertheSnowballEarthscenario.

Anewleaf

Whentreesfirstappearedabout380millionyearsago,theyalsodisturbedEarth'satmosphericbalance.

Unlikeanimals,plantsbreatheincarbondioxideandexpeloxygen.Treestransformsomeofthatatmosphericcarbonintolignin(木质素)--themajorconstituentofwoodandoneofthemostabundantproteinsontheplanet.Ligninisresistanttodecay,sowhenatreedies,muchofitscarbonbecomesburiedinsteadofreleasedbackintotheatmosphereascarbondioxide.LesscarbondioxideintheatmospherethinstheblanketofgasesthatkeepsEarthwarm,andthatcoolingeffectcantriggerglobalcooling,possiblyevenaniceage.

"Therewassomeglaciationthatstartedaroundthatperiodthatwasdrivenatleastinpartbytheevolutionoflandplants,"Koppsaidinatelephoneinterview.

Treesalsoaffectedtheglobalcarboncycleinanotherindirectway.Astheytunnelthroughtheground,treerootsbreakdownsilicaterocksintosedimentandsoil.Silicaterockcontainslargeamountsofcalciumandmagnesium(镁).Whentheseelementsareexposedtoair,theyreactwithatmosphericcarbondioxidetoformcalciumcarbonate(碳酸盐)andmagnesiumcarbonate,compoundsthatarewidespreadonEarth.

Thehumandifference

ThoughitmightseemasifhumansaremerefleasalongforarideonthebackofanimmenseanimalcalledEarth,ourintelligence,technologyandsheernumbersmeanourspeciespacksapunchthatcanshaketheworldinwildways.

Whilewearenotthefirstspeciestodrasticallyalterourplanet,ourinfluenceisuniqueinanumberofways,scientistssay.

Foronething,humanshavedevelopedlarge-scaleindustry,saidSpencerWeart,asciencehistorianattheAmericanInstituteofPhysics."Wearecapableofmobilizingthingsbeyondourownbiology,"Weartsaid."Iemitacertainamountofcarbondioxide,butmyautomobileemitsfarmore."

AnotheristherateatwhichhumansarewarmingEarth.

"Humansarethemostcommonlargeanimaltoeverwalktheplanet,"saidKirkJohnson,achiefcuratorattheDenverMuseumofNature&Science:

"Population,plusbrainpowerandtechnology,isapotentcombinationandtheresultisthathumansareeffectingchangeatveryhighrates."

Belnapagrees."Idon'tthinkwe'vefundamentallychangedanyprocess.We'vejustcrankedupthespeed,"shesaid."Wehaven'tintroducedanythingnew.We'vejustchangedhowfastorslowithappens,andmostlyfast."

Butnomatterhowhighhumanscausethetemperaturetoriseandhowmuchdamagewedototheplanet,Earthandlifewillsurvive,scientistssay.Itjustmightnolongerbeintheformwepreferortheformthatallowsustothrive.

"WhatweneedtobethinkingofashumanscausingchangestotheEarthsystemiswhattheconsequenceswillbetoushumanbeings,"saidEdwards,theUSCgeo-microbiologist."TheEarthcouldcareless.WewillberecordedasaminorchaosintheEarthsystem.TheEarthwillgoon.Thequestionis:

Willwe?

"

1.Accordingtotheworldwidereport,whatisthemainreasonforglobalwarming?

A)Americanpeople.B)People'sactivity.

C)Industryactivity.D)Developedcountries.

2.Thephotosynthesisbyancientmicrobesisanexampleof______.

A)thechangeofEarthB)thelonghistoryofEarth

C)thelife'sinfluencesonEarthD)thepowerofsunlight

3.AccordingtoEdwards,themicrobesarenow______.

A)recognizedbymostpeopleB)neglectedbymostpeople

C)diedoutfromtheEarthD)outofactionoftheEarthsystem

4.Whatisthemainfunctionofcyanobacteria?

A)Tomakemoreduststorms.B)Tokeepthesoilflying.

C)Tokeepthesoiltotheground.D)Tocreatemorerocks.

5.TokeeptheEarthoutofwarm,wecandestroytheMethanewith______.

A)greenhousegasB)sunlight

C)waterD)oxygen

6.Theearthisunfrozentodaywiththeappearanceof______.

A)themethaneblanketB)amile-thicklayerofice

C)newlifeformsD)thecarbondioxide

7.Differentfromanimals,thetreesinfluencetheearth'satmosphereby______.

A)expellingcarbondioxidefromtheirleaves

B)expellingoxygenfromtheirleaves

C)directlyreducetheblanketofgases

D)turningsomecarbondioxideintolignin

8.Treescanindirectlyhelptheexpositionofcalciumandmagnesiumwiththeirroots______.

9.Eventhoughnotthefirsttoinfluencetheearth,thehumanisstillalteringtheplanetin______.

10.Undertheinfluenceofhightemperatureandmuchdamagecausedbythehuman,Earthandlifewill______.

PartⅢListeningComprehension(35minutes)

SectionA

Directions:

Inthissection,youwillhearSshortconversationsand2longconversations.Attheendofeachconversation,

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