大学英语四级模拟试题及答题详解.docx
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大学英语四级模拟试题及答题详解.docx
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大学英语四级模拟试题及答题详解
大学英语四级模拟试题及答题详解
PartIReadingComprehension(SkimmingandScanning)(15minutes)
Directions:
Inthispart,youwillhave15minutestogooverthepassagequicklyandanswerthequestionsonAnswerSheet1.
Forquestions1-7,mark
Y(forYES)ifthestatementagreeswiththeinformationgiveninthepassage;
N(forNO)ifthestatementcontradictstheinformationgiveninthepassage;
NG(forNOTGIVEN)iftheinformationisnotgiveninthepassage.
Forquestions8-10,completethesentenceswiththeinformationgiveninthepassage.
Sleep
Sleepisoneofthosefunnythingsaboutbeingahumanbeing---youjusthavetodoit.Haveyoueverwonderedwhy?
Andwhataboutthecrazydreams,liketheonewhereabadpersonischasingyouandyoucan’trunoryell.Doesthatmakeanysense?
CharacteristicsofSleep
Whenweseesomeonesleeping,werecognizethefollowingcharacteristics:
Ifpossible,thepersonwillliedowntogotosleep.
Theperson’seyesareclosed.
Thepersondoesn’thearanythingunlessitisaloudnoise.
Thepersonbreathesinaslow,rhythmicpattern.
Theperson’smusclesarecompletelyrelaxed.Ifsittingup,thepersonmayfalloutofhisorherchairassleepdeepens.
Duringsleep,thepersonoccasionallyrollsoverorrearrangeshisorherbody.Thishappensapproximatelyonceortwiceanhour.Thismaybethebody’swayofmakingsurethatnopartofthebodyorskinhasitscirculationcutofffortoolongaperiodoftime.
Inadditiontotheseoutwardsigns,theheartslowsdownandthebraindoessomeprettyfunkythings.
Inotherwords,asleepingpersonisunconscioustomostthingshappeningintheenvironment.Thebiggestdifferencebetweensomeonewhoisasleepandsomeonewhohasfaintedorgoneintoacomaisthefactthatasleepingpersoncanbearousedifthestimuluspresentedbyisstrongenough.Ifyoushaketheperson,yellloudlyorflashabrightlight,asleepingpersonwillwakeup.
WhoSleeps?
Reptiles(爬行动物),birdsandmammalsallsleep.Thatis,theybecomeunconscioustotheirsurroundingsforperiodsoftime.Somefishandamphibians(两栖动物)reducetheirawarenessbutdonoteverbecomeunconsciouslikethehighervertebrates(脊椎动物)do.Insectsdonotappeartosleep,althoughtheymaybecomeinactiveindaylightordarkness.
Bystudyingbrainwaves,itisknownthatreptilesdonotdream.Birdsdreamalittle.Mammalsalldreamduringsleep.
Differentanimalssleepindifferentways.Someanimals,likehumans,prefertosleepinonelongsession.Otheranimalsliketosleepinmanyshortbursts.Somesleepatnight,whileotherssleepduringtheday.
SleepandtheBrain
Ifyouattachanelectroencephalographtoaperson’shead,youcanrecordtheperson’sbrainwaveactivity.Anawakeandrelaxedpersongeneratesalphawaves,whichareconsistentoscillationsatabout10cyclespersecond.Analertpersongeneratesbetawaves,whichareabouttwiceasfast.
Duringsleep,twoslowerpatternscalledthetawavesanddeltawavestakeover.Thetawaveshaveoscillationsintherangeof3.5to7cyclespersecond,anddeltawaveshaveoscillationsoflessthan3.5cyclespersecond.Asapersonfallsasleepandsleepdeepens,thebrainwavepatternsslowdown.Apersondeepindeltawavesleepishardesttowakeup.
REMSleep
Atseveralpointsduringthenight,somethingunexpectedhappens--rapideyemovement(REM)sleepoccurs.MostpeopleexperiencethreetofiveintervalsofREMsleeppernight,andbrainwavesduringthisperiodspeeduptoawakelevels.IfyoueverwatchapersonoradogexperiencingREMsleep,youwillseetheireyesflickeringbackandforthrapidly.Inmanydogsandsomepeople,arms,legsandfacialmuscleswilltwitchduringREMsleep.PeriodsofsleepotherthanREMsleepareknownasNREM(non-REM)sleep.
REMsleepiswhenyoudream.IfyouwakeupapersonduringREMsleep,thepersoncanvividlyrecalldreams.IfyouwakeupapersonduringNREMsleep,generallythepersonwillnotbedreaming.
YoumusthavebothREMandNREMsleeptogetagoodnight’ssleep.Anormalpersonwillspendabout25percentofthenightinREMsleep,andtherestinNREM.AREMsessionadream--lastsfiveto30minutes.
WhenYouMissSomeZzzzs…
Onewaytounderstandwhywesleepistolookatwhathappenswhenwedon’tgetenough:
Asyouknowifyouhaveeverpulledanall-nighter,missingonenightofsleepisnotfatal.Apersonwillgenerallybeirritableduringthenextdayandwilleitherslowdown(becometiredeasily)orwillbetotallywiredbecauseofadrenalin(肾上腺素)。
Ifapersonmissestwonightsofsleep,itgetsworse.Concentrationisdifficult,andattentionspanfallsbythewayside.Mistakesincrease.
Afterthreedays,apersonwillstarttohallucinateandclearthinkingisimpossible.Withcontinuedwakefulnessapersoncanlosegraspofreality.Ratsforcedtostayawakecontinuouslywilleventuallydie,provingthatsleepisessential.
Apersonwhogetsjustafewhoursofsleeppernightcanexperiencemanyofthesameproblemsovertime.
Twootherthingsareknowntohappenduringsleep.Growthhormoneinchildrenissecretedduringsleep,andchemicalsimportanttotheimmunesystemaresecretedduringsleep.Youcanbecomemorepronetodiseaseifyoudon’tgetenoughsleep,andachild’sgrowthcanbestunted(阻碍)bysleepdeprivation.
WhySleep?
Noonereallyknowswhywesleep.But,thereareallkindsoftheories,includingthese:
Sleepgivesthebodyachancetorepairmusclesandothertissues,replaceagingordeadcells,etc.
Sleepgivesthebrainachancetoorganizeandarchivememories.Dreamsarethoughtbysometobepartofthisprocess.
Sleeplowersourenergyconsumption,soweneedthreemealsadayratherthanfourorfive.Sincewecan’tdoanythinginthedarkanyway,wemightaswell"turnoff"andsavetheenergy.
Whatweallknowisthat,withagoodnight’ssleep,everythinglooksandfeelsbetterinthemorning.Boththebrainandthebodyarerefreshedandreadyforanewday.
Dreams
Thebraincreatesdreamsthroughrandomelectricalactivity.Randomisthekeywordhere.Aboutevery90minutesthebrainstemsendselectricalimpulsesthroughoutthebrain,innoparticularorderorfashion.Theanalyticportionofthebrain--theforebrain----thendesperatelytriestomakesenseofthesesignals.ItislikelookingataRorschachtest,arandomsplashofinkonpaper.Theonlywayofcomprehendingitisbyviewingthedream(ortheinkblot)metaphorically,symbolically,sincethere’snoliteralmessage.
Thisdoesn’tmeanthatdreamsaremeaninglessorshouldbeignored.Howourforebrainschooseto"analyze"therandomanddiscontinuousimagesmaytellussomethingaboutourselves,justaswhatweseeinaninkblotcanberevelatory.Andperhapsthereisapurposetothecraziness:
Ourmindsmaybeworkingondeep-seatedproblemsthroughthesecircuitousandlessthreateningmetaphoricaldreams.
Herearesomeotherthingsyoumayhavenoticedaboutyourdreams:
Dreamstellastory.TheyarelikeaTVshow,withscenes,charactersandprops.
Dreamsareegocentric.Theyalmostalwaysinvolveyou.
Dreamsincorporatethingsthathavehappenedtoyourecently.Theycanalsoincorporate
deepwishesandfears.
Anoiseintheenvironmentisoftenworkedintoadreaminsomeway,givingsomecredibilitytotheideathatdreamsaresimplythebrain’sresponsetorandomimpulses.
Youusuallycannotcontroladream--infact,manydreamsemphasizeyourlackofcontrolbymakingitimpossibletorunoryell.
Dreamingisimportant.Insleepexperimentswhereapersoniswokenupeverytimehe/sheentersREMsleep,thepersonbecomesincreasinglyimpatientanduncomfortableovertime.
HowMuchSleepDoINeed?
Mostadultpeopleseemtoneedseventoninehoursofsleepanight.Thisisanaverage,anditisalsosubjective.You,forexample,probablyknowhowmuchsleepyouneedinanaveragenighttofeelyourbest.
Theamountofsleepyouneeddecreaseswithage.Anewbornbabymightsleep20hoursaday.Byagefour,theaverageis12hoursaday.Byage10,theaveragefallsto10hoursaday.Seniorcitizenscanoftengetbywithsixorsevenhoursaday.
1.Thispassagetellsuswhypeoplehavetosleepandwhatcausesdreams.
2.Duringsleep,thepersonisconscioustomostthingshappeningintheenvironment.
3.Neitherreptilesnorbirdsdreamduringsleep.
4.AnormalpersonspendsthemainpartofthenightinNREMsleep.
5.Ifyoumissonenightofsleep,youwillloseyourappetitetosomeextent.
6.Nobodyreallyknowsthereasonwhywesleep.
7.Generallyspeaking,youneedlessamountofsleepasyougrowolder.
8.Theslower,thedeeperthesleep.
9.REMinthispassagestandsfor________________________.
10.Thebrainstemsendselectricalimpulsesthroughoutthebrainaboutevery________________
PartIVReadingComprehension(ReadinginDepth)(25minutes)
SectionA
Directions:
Inthissection,thereisapassagewithtenblanks.Youarerequiredtoselectonewordforeachblankfromalistofchoicesgiveninawordbankfollowingthepassage.Readthepassagethroughcarefullybeforemakingyourchoices.Eachchoiceinthebankisidentifiedbyaletter.PleasemarkthecorrespondingletterforeachitemonAnswerSheet2withasinglelinethroughthecentre.Youmaynotuseanyofthewordsinthebankmorethanonce.
Questions47to56arebasedonthefollowingpassage.
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