完整word版英语四级快速阅读专项练习含答案解析推荐文档Word文件下载.docx
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Suddenlysensitivenerveendingintheshark’sskinpickedupvibrationsofastrugglingfish.Thesharkwasimmediatelytransformedintoadeadly,efficientmachineofdeath.Withmusclestaut,thesharkknifedthroughthewateratarapidspeed.Inaflashthesharkcaughtitsvictim,alargefish,initspowerfuljaws.Then,jerkingitsheadbackandforth,thesharktorehugechunksoffleshfromitsvictimandswallowedthem.Soontheactionwasover.
MovingtoSurvive
Inpursuingitsprey,thesharkdemonstratedinadramaticwaytheimportantroleofmovement,orlocomotion,inanimals.
Liketheshark,mostanimalsusemovementtofindfood.Theyalsouselocomotiontoescapeenemies,findamate,andexplorenewterritories.Themethodsoflocomotionincludecrawling,hopping,slithering,flying,swimming,orwalking.
Humanshavetheaddedadvantageofusingtheirvariousinventionstomoveaboutinjustaboutanykindofenvironment.Automobiles,rockets,andsubmarinestransporthumansfromdeepoceanstoasfarawayasthemoon.However,forotheranimalsmovementcameaboutnaturallythroughmillionsofyearsofevolution.Oneofthemostsuccessfulexamplesofanimallocomotionisthatoftheshark.Itsabilitytoquicklyzeroinonitspreyhasalwaysimpressedscientists.ButittookadetailedstudybyDukeUniversitymarinebiologistsS.A.Wainwright,F.Vosburgh,andJ.H.Hebranktofindouthowthesharksdidit.IntheirstudythescientistsobservedsharksswimminginatankatMarinelandinSaintAugustine,Fla.Moviesweretakenofthesharks’movementsandanalyzed.Studieswerealsomadeofsharkskinandmuscle.
SkinIstheKey
Thebiologistsdiscoveredthattheskinofthesharkisthekeytotheanimal’shighefficiencyinswimmingthroughthewater.Theskincontainsmanyfibersthatcrisscrossliketheinsideofabeltedradialtire.Thefibersarecalledcollagenfibers.Thesefiberscaneitherstoreorreleaselargeamountsofenergydependingonwhetherthefibersarerelaxedortaut.Whenthefibersarestretched,energyisstoredinthemthewayenergyisstoredinthestringofabowwhenpulledtight.Whentheenergyisreleased,thefibersbecomerelaxed.
TheDukeUniversitybiologistshavefoundthatthegreateststretchingoccurswherethesharkbendsitsbodywhileswimming.Duringthebody’sbackandforthmotion,fibersalongtheoutsidepartofthebendingbodystretchgreatly.Muchpotentialenergyisstoredinthefibers.Thisenergyisreleasedwhentheshark’sbodysnapsbacktheotherway.
Asenergyisalternatelystoredandreleasedonbothsidesoftheanimal’sbody,thetailwhipsstronglybackandforth.Thiswhip-likeactionpropelstheanimalthroughthewaterlikealivingbullet.
SourceofEnergy
Whatcausesthefiberstostoresomuchenergy?
InfindingtheanswertheDukeUniversityscientistslearnedthattheshark’ssimilaritytoabeltedradialtiredoesn’tstopwiththeskin.Justasaradialtireisinflatedbypressure,so,too,istheareajustundertheshark’scollagen“radials”.Insteadofairpressure,however,thepressureinthesharkmaybeduetotheforceofthebloodpressingonthecollagenfibers.
Whenthesharkswimsslowly,thepressureonthefibersisrelativelylow.Thefibersaremorerelaxed,andthesharkisabletobenditsbodyatsharpangles.Theanimalswimsthiswaywhenlookingaroundforfoodorjustswimming.However,whenthesharkdetectsanimportantfoodsource,somefantasticinvoluntarychangestakeplace.
Thepressureinsidetheanimalmayincreaseby10times.Thispressurechangegreatlystretchesthefibers,enablingmuchenergytobestored.
Thisenergyisthentransferredtothetail,andthesharkisoff.Therestofthestoryispredictable.
DolphinHasSpeedRecord
Anotherfastmarineanimalisthedolphin.Thisseagoingmammalhasbeenclockedatspeedsof32kilometers（20miles）anhour.Biologistsstudyingthedolphinhavediscoveredthat,liketheshark,theanimal’sefficientlocomotioncanbetracedtoitsskin.Adolphin’sskinismadeupinsuchawaythatitoffersverylittleresistancetothewaterflowingoverit.Normallywhenafishorotherobjectmovesslowlythroughthewater,thewaterflowssmoothlypastthebody.Thissmoothflowisknownaslaminarflow.However,atfasterspeedsthewaterbecomesmoreturbulentalongthemovingfish.Thisturbulencemusesfrictionandslowsthefishdown.
Inadolphintheskinissoflexiblethatitbendsandyieldstothewavinessofthewater.Thewaves,ineffect,becometuckedintotheskin’sfolds.Thisallowstherestofthewatertomovesmoothlybyinalaminarflow.Whereotheranimalswouldbeslowedbyturbulentwateratrapidspeeds,thedolphincanracethroughthewateratrecordbreakingspeeds.
OtherAnimalsLessEfficient
Notallanimalsmoveasefficientlyassharksanddolphins.Perhapsthegreatestloserinlocomotionefficiencyistheslug.Theslug,whichlookslikeasnailwithoutashell,laysdownaslimytrailoverwhichitcrawls.Itusessomuchenergyproducingtheslimymucusandcrawlingoveritthatamousetravelingthesamedistanceusesonlyonetwelfthasmuchenergy.
Scientistssaythatbecauseoftheslug’sinefficientuseofenergy,itslifestylemustberestricted.Thatis,theanimalsareforcedtoconfinethemselvestosmallareasforobtainingfoodandfindingproperlivingconditions.Havehumanseverbeenfacedwiththiskindofproblem?
1.Accordingtothepassage,asharkcanusemovementtodosomethingexcept____________.
[A]tofindfood
[B]toavoidbeingchasedbyitsenemies
[C]tofindanewplacetolive
[D]toshowitsbraveness
2.Examplesofautomobiles,rocketsandsubmarinesareusedtoshowthat_______________.
[A]humansarethemostcleverlivingcreaturesintheworld
[B]humaninventionsenableustotravelinalmostanykindofenvironment
[C]humansareverysuccessfulininventingtransportationtools
[D]humanscan’tmovelikeotheranimalsinanycircumstances
3.Whatisthekeytotheshark’sswiftlocomotioninwater?
[A]Theskin.[B]Thetail.[C]Themuscle.[D]Thejaw.
4.AccordingtotheDukeUniversityscientists,whendoesthesharkstretchitscollagenfiberstothegreatestextent?
[A]Whenmovingitstailrapidly.
[B]Whenfindingitspreys.
[C]Whenstayingwithoutanymovement.
[D]Whenbendingitsbodyinswimming.
5.Whyistheareajustundertheshark’scollagenfiberssimilartoabeltedradialtire?
[A]Becauseitisalsofullofbloodpressure.
[B]Becauseitisalsofilledofairpressure.
[C]Becauseitisalsoinflatedbypressure.
[D]Becauseitalsocanbeusedagainandagain.
6.Alaminarflowisformedwhenafishswims________________.
[A]slowlythroughthewater
[B]rapidlythroughthewater
[C]againstthecurrent [D]atthefastestspeedinwater
7.Consumingtheequalamountofenergyasaslugdoes,amousecantravel_________aslongasaslug.
[A]onetwelfthtimes
[B]thesame
[C]12times
[D]1.2times
8.Asharkfindsitspreyby________________.
9.Accordingtothepassage,_______________canbecomparedtothestringofabowforbothofthemstoreenergywhenstretched.
10.Whenthesharkdetectsanimportantfoodsource,_______________________takeplace.
（二）
Inthispart,youwillhave15minutestogooverthepassagequicklyandanswerthequestionsonAnswerSheet1.Forquestions1-7,choosethebestanswerfromthefourchoicesmarkedEAI,IB3,ICIandIDa.Forquestions8-10,completethesentenceswiththeinformationgiveninthepassage.
AboutStoryReader
Parentsdearlyhopetheirchildrenlearntoreadwell.Theyalsohopetheirchildrenlearntoreadquicklyandeasily,sothatthey’rereadyforthedemandsputonthembyschoolandtheworld.
Kidswanttolearnhowtoread,buttheyalsocraveentertainment,whetherit’squietandpassiveordynamicandinteractive.TheaimsoftheStoryReaderlineofelectronicbooksaretoentertainchildrenandtointroducethemtotheprocess
oflearninghowtoreadinagentleandenjoyableway.Inthisarticle,we’llshowyouhowStoryReaderworksandifitaccomplishesthatgoal.
StoryReaderisacompact,roughly12-inch-by-12-inchplasticcase（withacarryinghandle）thatopenstorevealanactualbookthatfitssnuglyintotheReaderitself.StoryReader’scorefeatureisthatit"
reads"
thebookaloudtoachildashefollowsalong.ThechildturnsthepageswhenpromptedbytheStoryReaderorathisownpace.
Bookshavebothtextandillustrations.Theelectronicbookrespondstothechild’swishes.TheStoryReaderspeaksthetextforthecurrentpage.Ifthechildturnsbackafewpages,theReaderrecognizesthatpageandreadsitagain.Kidsreactwelltothisinteractivitybecauseitinstillsasenseofcuntroloverthestory.
ThereareThreeStoryReaderProducts
ThebasicStoryReader,introducedin2003,isasdescribedaboveandisintendedforkidsthreeyearsofageandolder.
Eachbookhasasmallcompanioncartridgethatslidesintoaportonthecaseandcontainstheaudioencodedintoitsmemor
升级会员 