自考英语历年真题汇编

自考英语历年真题汇编

2006年10月

2000年(上)自考英语(一)试题

I.VocabularyandStructure(10points,1pointforeach)从下列各句四个选项中选出一个最佳答案。

1.Somepeoplewhoareveryintelligentandsuccessfulintheirfieldsfind___difficulttosucceedin

languagelearning.

A.themB.themselvesC.itD.itself

2.Televisionadsareshort,buttheyarerepeatedoverandoveragain___theaudienceseesandhears

themmanytimes.

A.inthatB.sothatC.astoD.soas

3.TheAtlanticOceanisonlyhalfasbigasthePacific,itisstillverylarge.

A.butB.andC.soD.therefore

4.Noonehasbeenabletoprovethatfishisbetterforthebrainthanmanyotherkindsoffood.

A.someB.soC.asD.any

5.Tomatoeswereoncecalledloveapplesandweresupposedtomakethosewhoatethem_inlove.

A.fellB.feelC.fallD.felt

6.Washingfooddownwithwaterasa__forchewingisnotagoodhabit.

A.directionB.substituteC.possibilityD.resource

7.Itisimportanttorealizethatthesametechnology__helpsusmayalsoharmus.

A.asB.thatC.whatD.when

8.Sciencebegantodeveloprapidlywhenmanlaid___hiswrongbeliefsandbegantoseektrue

explanations.

A.outB.downC.asideD.outside

9.Remember,nothinghurtsconcentration___readingtooslowly.

A.ratherthanB.aswellasC.morethanD.insteadof

10.Moreandmorepeoplearerealizingthatthereisabetweenheartdiseaseandthewayonelives.

A.correspondenceB.comparisonC.connectionD.consequence

II.ClozeTest(10points,1pointforeach)

下列短文中有十个空白，每个空白有四个选项。根据上下文要求选出最佳答案。

Fearanditscompanionpainaretwoofthemostusefulthingsthatmenandanimalspossess,ifthey

areproperlyused.Iffiredidnothurtwhenitburnt,childrenwouldplaywithit11theirhandswere

burntaway.12,ifpainexistedbutfeardidnot,achildwouldburnitselfagainandagain,becausefear

wouldnot13ittokeepawayfromthefirethathadburntitbefore.Fearandpainarethereforetwo

guards,14whichmenandanimalsmightsoondieout.Inthefirstsentencewesuggestthatfearought

tobeproperlyused.If,15,younevergooutofyourhouse16ofthedangerofbeingknockeddown

andkilledinthestreetbyacar,youarelettingfearruleyoutoo17.Eveninyourhouseyouarenot

absolutely18:anairplanemaycrashonyourhouseoryoumaygetcancer!Theimportantthingisnot

toletfearruleyou,but19tousefearasyourservantandguide.Fearwillwarnyouofdangers;20

youhavetodecidewhatactiontotake.

11.A.becauseB.ifC.thoughD.until

12.A.GenerallyB.ProbablyC.SimilarlyD.Consequently

13.A.warnB.requestC.manageD.protect

14.A.withB.withoutC.forD.against

15.A.afterallB.bychanceC.forexampleD.infact

16.A.regardlessB.becauseC.intermsD.infront

17.A.littleB.moreC.manyD.much

18.A.firmB.calmC.safeD.strong

19.A.insteadB.betterC.similarlyD.further

20.A.thenB.otherwiseC.likewiseD.even

III.ReadingComprehension（30points,2pointsforeach）

从下列每篇短文的问题后所给的四个选择项中选出一个最佳答案。

PassageOne

Questions21to25arebasedonthefollowingpassage.

Theproblemofleisureisnew.Untilveryrecenttimespeopleworkedeachdaytothelimitoftheir

strength.Ofcoursetherewerealwaysaprivileged（有特权的）fewwhohadleisure;butmostmenhadto

work12,14,oreven16hoursaday,sixdaysaweek.Aslateas1840theaveragefactoryworkerlabored

72hoursaweek."Sunuptosundown"wasthefarmer'sday,orasanotherphraseputsit,"fromcanto

can't”.Today,workinglessthana40-hourweek,peopleenjoymoreleisuretime.Hence,thewiseuseof

leisuretimehasbecomeanimportantproblemforeveryone,youngorold.Itisaparticularlydifficult

problemforthesick,theaged,andthosewhohaveretiredfromearningaliving.Thosepeoplehaveso

muchleisurethatitishardforthemtofindinterestingandworthwhilewaystouseit.

Howevershorttheworkweekbecomes,workisstillthemostimportantpartoflife.Wedonotwork

togetleisureandthepleasuresleisurebringsus;rather,weuseleisurewiselysothatworkitselfcan

becomeawardingandenjoyable.Thefeelingofsuccessatdoingone'sdailywork—whetheritisajob,

maintainingahome,orgoingtoschool-dependslargelyoncomingtoiteachdaywithfreshenergyand

activeinterest.

Leisureandrecreation（消遣）gotogether,thoughtheyarenotnecessarilythesamething.

"Recreationnhasanobviousmeaning.Itisthekindofleisureactivitythatbrings"re-creation"ofstrength

andspirit.Whenonespeaksofmakinggooduseofleisure,hemeanschoosingrecreationalactivities

whichcontributetohealth,growth,andspirit.

21.Thephrasenfromcantocan't,'inParagraph1means.

A.frombeginningtoendB.frombirthtodeath

C.frommorningtonightD.fromtimetotime

22.Howtospendleisuretimewiselyisnotaparticularlydifficultproblemforpeople___.

A.whoareverybusyeverydayB.whoaresickinbed

C.whoareagedandingoodhealthD.whohaveretiredfromwork

23.Howdoestheauthorlookatworkandleisure?

A.Weworkhardsothatwecanenjoymoreleisure.

B.Weenjoyleisuresothatwecancomebacktoworkwithfreshenergy.

C.Leisurecanbringusalotofpleasuresthatworkcannot.

D.Thesuccessofworkhaslittletodowithhowwespendourleisuretime.

24.Whatistherelationshipbetweenleisureandrecreation,accordingtotheauthor?

A.Leisureandrecreationarecloselyrelated.

B.Leisureandrecreationareidentical.

C.Recreationcoversallkindsofleisureactivities.

D.Recreationdoesnotbelongtoanyleisureactivity.

25.Fromthepassageweknowthat___.

A.leisurehasbeenanoldproblemsinceancienttimes

B.leisurecannotbereplacedasthemostimportantpartoflife

C.oursuccessinworkismostlydeterminedbywhetherweuseleisurewisely

D.goodrecreationalactivitiescontributegreatlytohealth,growthandspirit

PassageTwo

Questions26to30arebasedonthefollowingpassage.

Eachnationhasitsownpeculiarcharacterwhichdistinguishesitfromothers.Butthepeoplesofthe

worldhavemorepointsincommonthanpointsinwhichtheydiffer.Onetypeofpersonthatiscommonin

everycountryistheonewhoalwaystriestodoaslittleaspossibleandtogetasmuchaspossibleinreturn.

Hisopposite,themanwhoisinthehabitofdoingmorethanisstrictlynecessaryandwhoisreadyto

acceptwhatisofferedinreturn,israreeverywhere.

Boththesetypesareusuallyunconsciousoftheircharacter.Themanwhoavoidseffortisalways

talkingabouthis"rights":heappearstothinkthatsocietyoweshimapleasant,easylife.Themanwho

triestodoaslittleashecanisalwaysfullofexcuses:ifhehasneglectedtodosomething,itwasbecause

hehadaheadache,ortheweatherwastoohot—ortoocold—orbecausehewaspreventedbybadluck.At

first,otherpeople,suchashisfriendsandhisemployer,generouslyaccepthisstories;butsoontheyrealize

whatkindofpersonheis.Inthelongrunhedeceivesonlyhimself.Whenhisfriendsbecomecooltowards

himandhefailstomakeprogressinhisjob,heissurprisedandhurt.Heblameseveryoneandeverything

excepthimself.Hefeelsthatsocietyisfailinginitsdutiestowardshim,andthatheisbeingunjustly

treated.

26.ThecentralideaofParagraph1isthat.

A.eachnationispeculiarenoughtoenableustodistinguishitfromothers

B.thepeoplesoftheworldareasalikeastheyaredifferent

C.thepeoplesoftheworldhavemoresimilaritiesthandifferences

D.thosewhodomorethanisstrictlynecessaryarecommonineverycountry

27.AccordingtoParagraph1,themanwhodoesmorethanisrequired____.

A.isreadytoacceptwhatthesocietyoffershimB.expectsnothinginreturnfbrhiswork

C.feelsthatheisunderheavydebtD.thinksthismakeshislifeeasy

28.Thosewhotrytodoaslittleaspossible__.

A.envyothers*goodluckB.aregoodstory-tellers

C.supplyfalsereasonsfortheirlackofresponsibilityD.thinkthattheiroppositesowethemapleasantlife

29.Thephrase"inthelongrun"(Paragraph3)isclosestinmeaningto"

A.inpracticeB.intheendC.ineffectD.innotime

30.Itcanbeinferredfromthepassagethatpeoplewhocheat____.

A.willbeunjustlytreatedB.willcheatonlythemselveseventually

C.willchangetheirbehaviorD.willgetsurprisedbytheirownstories

PassageThree

Questions31to35arebasedonthefollowingpassage.

Thegovernmentmaycontrolpriceswhenthereisaproblemsuchasrapidlyincreasingrentsorarise

inthecostofliving.Whenthegovernmentcontrolsprices,thereisnolongeranormalrelationship

betweenthepriceofaproductandthequantityconsumerswillbuy.Governmentcontrolsmayhelpinan

emergency（紧急情况）.However,someeconomistsbelievethatcontrolscanhavenegativeeffectsovera

longperiodoftime.

Incitieswithrentcontrol,thecitygovernmentsetsthemaximumrentthatalandlord（房主）can

chargeforanapartment.Supportersofrentcontrolarguethatitprotectspeoplewhoarelivingin

apartments.Theirrentcannotincrease;therefore,theyarenotindangeroflosingtheirhomes.However,

thecritics（评论者）saythatafteralongtime,rentcontrolmayhavenegativeeffects.Landlordsknowthat

theycannotincreasetheirprofits.Therefore,theyinvestinotherbusinesseswheretheycanincreasetheir

profits.Theydonotinvestinnewbuildingswhichwouldalsoberent-controlled.Asaresult,new

apartmentsarenotbuilt.Manypeoplewhoneedapartmentscannotfindany.Accordingtothecritics,the

endresultofrentcontrolisashortageofapartmentsinthecity.

Economictheorypredictstheresultsofeconomicdecisionssuchasdecisionsaboutrentcontrol,price

controlandtheminimumwage.Thepredictionsmaybecorrectonlyifnotherthingsareequal."

Economistsdonotagreeonsomeofthepredictions.Theyalsodonotagreeonthevalueofdifferent

decisions.Someeconomistssupportaparticulardecisionwhileotherscriticizeit.Economistsdoagree,

however,thattherearenosimpleanswerstoeconomicquestions.

31.AccordingtoParagraph1,pricecontrol.

A.doesmoreharmthangoodB.isgoodineverysense

C.isnecessarybutharmfulinthelongtermD.shouldbeavoided

32.ItcanbeinferredfromParagraph2that.

A.thankstorentcontrol,itwouldbeeasierformanytofindapartments

B.landlordsmaytakebacktheirapartmentsiftherentistoolow

C.thetightertherentcontrolis,thelessnewapartmentswillbebuilt

D.landlordswillnotinvestinotherbusinessesafterpricecontrolisapprovedbythegovernment

33.Whichofthefollowingdoalleconomistsagreeon?

A.Controlscanhavenegativeeffectsoveralongperiodoftime.

B.Thegovernmentmusttakemeasurestocontrolrentincrease.

C.Themaximumrentsystemprotectspeoplewhodon'thavetheirownhouses.

D.Economicquestionsaredifficulttodealwith.

34.Theattitudeoftheauthortopricecontrolis.

A.subjectiveB.objectiveC.indifferentD.supportive

35.Thepurposeofthispassageisto.

A.argueB.persuadeC.analyzeD.describe

IV.WordSpelling（10points,1pointfortwowords）

将下列汉语单词译成英语。

36.广场n.s_________37.珍贵的ad.p_____________

38.口袋n.p_________39.假装v.p___________

40.各种各样的ad.v___________41.挑战n.c_____________

42.完美的ad.p___________43.想象v.i___________

44.包含v.c___________45.心脏n.h_______

46.直径n.d_____________47.海滩n.b_______

48.诚实的ad.h_____________49.坚持v.i_________

50.法官；裁判员n.j________51.最少ad.1_______

52.信息；口信n.m53.省略v.o

54.律师n.155.操作v.o

V.WordForm(10points,1pointforeach)将括号中的各词变为适当形式填入空白。

56.Sometimesinformationinthelong-termmemory__(be)hardtoremember.

57.Inthe1600rs,travelersfromEurope__(bring)backdiamondsfromIndia.

58.Insurancefundamentalscan___(understand)bythosewillingtostudythem.

59.Hewantedtheletter___(mail)atonce.

60.Webecomeusedto___(see)bloodonthenewsontelevision,orinfullcolorinnewspapersand

magazines.

61.Asagenerally__(accept)mediumofexchange,moneyrulesouttheneedforthedirectexchange

ofoneitemforanother.

62.Almosteveryonespendsaconsiderableamountofpresentmoments__(worry)aboutthefuture.

64.Well-organizedmaterialis__(well)rememberedthanjumbledinformation.

65.Ifwe__(nothave)air,therewouldbenosound.

VI.TranslationfromChineseintoEnglish(15points)将下列各句译成英语。

66.对初学者来说，用英语思维比说英语更难。

67.据说有些吃鹿肉的原始人能跑得象鹿一样飞快。

68.要是昨天他早一点回家，他的女儿就不会把他的手表拆了。

69.要找到与你观点相同的学生并不容易。

70.在你的朋友中有多少人从来未犯过法呢？

VII.TranslationfromEnglishintoChinese(15points)将下列短文译成汉语。

Manyoftheplantsandanimalsfromwhichourfoodcomescanproducethemselvesquitewell

withoutourhelp.Fish,forexample,liveandbreedaccordingtotheirownlifepattern.Human"producers"

thencomewithnetsandfishingpolestotakethefishfromthewater;

Inourspecializedworld,however,itisnotalwayspossibletoletourfoodgrowinitsownway.A

relativelysmallnumberofpeopleareresponsibleforproducinglargequantitiesoffood.Inorderto

performsuchafunctioneffectively,itisnecessaryforthemtoraisecattleandgrowcropsinafairly

concentratedarea.

Fishing,livestock(家畜)breeding,andfruit,vegetable,andgraingrowingareamongthemore

commonlyknownfood-productionindustries.

2000年(下)自考英语(一)试题

I.VocabularyandStructure(10points,Ipointforeach)从下列各句四个选项中选出一个最佳答案。

1.DeathandtaxesaretwothingsinlifethateveryAmericancanbesure__.

[A]of[B]for[C]at[D]with

2.TheAtlanticOceanisover6,000kmwhereChristopherColumbuscrossedit.

[A]deep[B]wide[C]long[D]across

3.Twomenweresittinginadoctor'swaitingroom.nWhatareyouinhere__?”askedone.

[A]for|B]to[C|on[D]about

4.Itisagoodideaforparentstomonitorthe___aswellasthekindoftelevisionthattheirpreschool

childwatches.

[A]number[B]size[C]amount[D]program

5.Inthegaragesale,eagerbuyersboughtallbut50oftheunwanteditemsinoneweekend,leavingthe

Ericksons$442__.

[A]rich[B]better[CJricher[DJgood

6.Manypeoplehavemadeatoaphysicalfitnessprogramsoastomaintaingoodhealth.

[A]decision[BJcommitment[C]contribution[DJdifference

7.Manyspeciesofanimalsareunderthethreatofbecauseoftherapidchangeofnatural

environment.

[A]guns[B]existence[C]hunters[D]extinction

8.TheknowledgeandpoweroftheInformationAgewillbewithinreachnotjustofthefew,ofevery

classroom,everylibraryinthenearfuture.

[A]but[B]instead[C]because[D]then

9.Generally,thechildrenstayinthenuclearfamilytheygrowupandmarry.

[A]although[B]as[C]until[D]where

10.Thedifferencebetweenthebabytwinsissosmall___itisevenhardfortheirMumtotell.

[A]as[B]that[C]since[D]if

ILClozeTest(10points,1pointforeach)

下列短文中有10个空白，每个空白有四个选项。根据上下文要求选出最佳答案。

Childrenarecuriousabouttheworldaroundthem.Forexample,theywanttoknow11theirhearts

beat.Theywanttoknowwhytheoceanwater12salty.13childrengrowup,theybecomecurious

aboutdifferentkindsofthings.Whentheyarebabies,theyareinterestedinthepartsoftheirbodiesandin

thesmilesoftheirmothers.14theybecomeinterestedinthephysicalworldaroundthemtheplants,

theanimals,thesky.Later,theybecomeinterestedinthethings15peoplehavemade:wheels,bicycles,

cars.Andwhentheyareadults,theircuriosity16.Sometimesthiscuriosityleadstoa17inscience.

Scientistsspendtheirlives18tofindoutabouttheworld.19whoworkwiththeearthsciences

studytheearth,theoceans,andtheskies.20scientistswhostudylivingworkwiththebiological

sciences.Athirdgroupofscientistsstudythephysicalsciences,e.g.physics,chemistry.

11.[A]what[B]how[C]which[D]when

12.[A]feels[B]smells[C]tastes[D]looks

13.[A]As[BJSince[C]Assoonas[D]Aslongas

14.[A]so|B|Even[C]Thus[D]Then

15.[A]that[BJwhom[C]why[D]inwhich

16.fA]exists(B]stops[C]continues[D]decreases

17.[A]work[B]research[C]field[D]career

18.[AJtry|B]totry[CJtrying[D]tried

19.[A]That|B]This[C]Those|D]These

20.[A]Other[B]Another[CJOthers(DJTheother

III.ReadingComprehension(30points,2pointsforeach)

从下列每篇短文的问题后所给的四个选择项中选出一个最佳答案。

PassageOne

Questions21to25arebasedonthefollowingpassage.

Foraclearerpictureofwhatthestudentknows,mostteachersuseanotherkindofexaminationin

additiontoobjectivetests.Theyuse"essay'*tests,whichrequirestudentstowritelonganswerstobroad,

generalquestionssuchasthefollowing:"MentionseveralwaysinwhichBenjaminFranklinhas

influencedthethinkingofpeopleinhisowncountryandinotherpartsoftheworld.'1

Oneadvantageoftheessaytestisthatitreducestheelementofluck.Thestudentcannotgetahigh

scorejustbymakingaluckyguess.Anotheradvantageisthatitshowstheexaminermoreaboutthe

student'sabilitytoputfactstogetherintoameaningfulwhole.Itshouldshowhowdeeplyhehasthought

aboutthesubject.Sometimes,though,essaytestsgavedisadvantages,too.Somestudentsareabletowrite

rathergoodanswerswithoutreallyknowingmuchaboutthesubject,whileotherstudentswhoactually

knowthematerialhavetroubleexpressingtheirideasintheessayform.

Besides,inanessaytestthestudent'sscoremaydependupontheexaminer'sfeelingsatthetimeof

readingtheanswer.Ifheisfeelingtiredorbored,thestudentmayreceivealowerscorethanheshould.

Anotherexaminerreadingthesameanswermightgiveitamuchhighermark.Becauseofthis,the

objectivetestgiveseachstudentafairerchance,andofcourseitiseasierandquickertoscore.

Whetheranobjectivetestoranessaytestisused,problemsarise.Whensomeobjectivequestionsare

usedalongwithsomeessayquestions,however,afairlyclearpictureofthestudent'sknowledgecan

usuallybeobtained.

21.Whatmayhavebeendiscussedinthepreviousparagraphs?

[A]Theessaytest.[B]Howteacherstesttheirstudents.

[C]Howstudentswritetheiressays.|D]Theobjectivetest.

22.Theessaytestispreferredbecause__.

[A]itshowsmoreaboutthestudent'sunderstandingofthesubject

[B]itteststhestudent'sknowledgeofthematerialaswellashisexpressionofideas

[C]Itgiveseachstudentafairerchance

[D]Itsscoringmaybeinfluencedbytheexaminer'sfeelings

23.Theword'this*(Line4,Para.3)referstothefactthat__.

[A]studentsmayreceivealowerscoreinanessaytest

[B|anotherexaminerusuallygivestheanswerahighermark

[C]differentexaminersmaygivethesameessaydifferentscores

[D]theobjectivetestgiveseachstudentafairerchance

24.Accordingtothepassage,whichofthefollowingstatementsabouttheobjectivetestisNOTtrue?

[A]Itismoreobjectivethantheessaytestintermsofscoring.

|B|Itallowsthestudenttoguessthecorrectanswerwithoutreallyknowingthematerial.

[C]Itshowsthestudent'sabilitytothinkaboutdifficultproblems.

[DJItiseasyandquicktoscore.

25.Accordingtotheauthor,anidealtestshouldbe__.

[A]anobjectivetest[B]anessaytest

[C]acombinationofthetwo[D]somethingnew

PassageTwo

Questions26to30arebasedonthefollowingpassage.

Aroundtheworldtwothirdsofthepeoplearefarmers.Mostofthemengageinsubsistencefarming.

Thismeansthattheyraiseplantsandanimalstofurnishtheirfamilieswithfoodandothersupplies.They

consumetheirvariedoutputandhavelittletosellortotradeforothergoods.Subsistencefarmswere

commonintheUnitedStatesatonetime,buttherearefewsuchfarmstoday.

TwothirdsofAmericanfarmerspracticecommercialfarming.Commercialfarmsproduceabout97

percentofthecountry'sagriculturalgoods.Thesefarmsareoperatedmuchlikeotherindustries.The

membersofthefarmfamilyproducethecommodities(商品)thatwillbesenttothemarket.Theysell

theirproductsandbuythethingstheyneed.

Somecommercialfarmsarebigfactoriesinthefield.Theymaybeownedbyacompanyorbyan

individualasaninvestment.MostAmericanfarms,however,arestilloperatedbyfamilies.Afarmermay

ownorrenthisland.

InacountryaslargeastheUnitedStates,farmsvarywidelyinclimate,landsurface,soil,water

supply,conveniencetomarket,andothercharacteristics.Differentregionsmayhavedifferentkindsof

specializedfarms.Specializedfarmersconcentrateonthekindoffarmingbestsuitedtothelandand

climate,totheirtechnicalskills,andtothemoneytheyinvestinthefarm.

However,noregionislimitedtoasingletypeoffarm.Indeedfewfarmsarelimitedtoonecropor

commodity.Whereoutputisvariedandnoonekindofcroporcommodityproducesmorethanhalfofa

farm'sincome,itisclassifiedasageneralfarm.Thegeneralfarmergrowsvariedcropstousethedifferent

kindsofsoilsorsurfacesonhislandandtoemployhistimeandmachinerymostefficiently.

26.Subsistencefarmers___.

[A]growcropsfortheirfamilies1ownuse[B]sellalotoftheirproductsformoney

[C]tradetheirvariedoutputforothergoods[D]usetheiragriculturalproductsascommodities

27.Subsistencefarms.

[A]areverypopularintheUnitedStatesnow

[B]arestillcommoninmanypartsoftheworld

[C]consistoftwothirdsofthetotalnumberofthefarmsintheworldtoday

[D]usedtobethemajorformoffarmingintheworld

28.Americancommercialfarms____.

[A]furnishthecountrywithtwothirdsofthefooditspeopleneed

[B]areruninmuchthesamewayasotherindustries

[CJareallownedbydifferentcompanies

|D]neverrenttheirlandforfarming

29.Aspecializedfarmischaracterizedby___.

[A]itsespeciallylargesize[B]itsindependenceofthemarket

[C]itsconcentrationonasingletypeoffarming[D]itsspecialwayofoperation

30.Afarmisclassifiedasgeneralif___.

[A]morethanhalfofitsincomecomesfromvariedcrops

[B|itislimitedtoasingletypeoffarm

[C]itemploysdifferentkindsofmachines

[D]thesoilsorsurfacesofitslandareusedmostefficiently

PassageThree

Questions31to35arebasedonthefollowingpassage.

Nooneknowsforsurewhybirdsmigrate（定期迁徙）.Onetheoryofmigrationsaysthatancientbirds

ofthenorthernpartoftheearthwereforcedsouthwardduringtheIceAge,whenicecoveredlargepartsof

Europe,AsiaandNorthAmerica.Astheicemelted,thebirdscamebacktotheirhomelands,spentthe

summer,andthenwentsouthagaininwinter.Gradually,thesecomingsandgoingsbecamehabits,and

birdsnowmigratethoughmuchoftheicehasgone.

Anothertheoryproposesthattheancienthomeofallmodernbirdswasthetropicareas.Therelived

sowellthattheregionbecameovercrowded.Manyspecieshadtomovenorthward.Duringthesummer,

thesebirdsfoundplentyofroomandfood.Inwinter,however,foodbecamescarceandtheyhadtoreturn

tothesouth.

Anewertheoryisthatincreasingdaylightstimulatescertainglands（腺）inthebird'sbodyand

preparesitformigration.Onescientistisabletomakebirdsmigrateinmidwinterbyexposingthemfor

twomonthstoartificialdaylight.Recoveriesofmarkedbirdsindicatethattheyflynorthassoonasthey

aresetfree.Theconclusionisthattheurgetomigrateisdeterminedbychangesinthebird'sbodywhich

takeplaceunderseasonalchangesinthelengthofdaylight.

Thistheorywouldaccountforthefactthatnotallbirdsmigrateatthesametime.Eachspeciesseems

tohaveitsownschedule.Thetheorywouldalsoaccountfortheregulartimeandroutesofmigration.

Birdsarriveatagivenplaceyearafteryear.

Unfavorableweatherdelaysthemonlyafewdays.Totalhoursofdaylight,ratherthanweather,start

themontheway.

Howbirdsfindtheirwaytothesameplaceyearafteryearandwhytheyfollowtheirownparticular

routearestillmysteries.Theyevidentlydonotfollowknownlandmarks(地面标志)，formanyyoung

birdsmigratealonewithoutthehelpofexperiencedadults.

31.Wecanconcludefromthefirstparagraphthat__.

[A]duringtheIceAge,