生物学段落练习（一）鱼的形体和水47.(A)Acomparisonoffishtowarm-bloodedanimals.(B)Thedifferencebetweensaltwaterandfreshwaterenvironments.(C)Theimportanceoffishtohumanbeings.(D)Howwaterhasaffectedthedevelopmentoffish.48.(A)Itcan’tbecompressed.(B)Itisoftenpolluted.(C)Itstemperatureoftenfluctuatesdramatically.(D)Itlimitstheirsize.49.(A)Awhale.(B)Ahuman.(C)Asnake.(D)Asnail.50.(A)Itsskeleton.(B)Itsshape.(C)Itssenses.(D)Itsbodytemperature.(MarineBiologyLecture)Tous,theenvironmentinwhichdwelloftenseemscold,darkandmisterioustedious.Buttherearetolivingin.Andthey'veplayedanimportantroleinmakingwhattheyare.Oneisthatwaterisn'tsubjecttosuddentemperaturechanges.Thereforeitmakesanexcellenthabitatforal.Anotheradvantageisthewater'sabilitytoeasilysupportbodyweight.Protoplasmhasapproximatelywater.Soafishinwaterisweightless.Thisweightlessnessinturnmeanstwothings:1)Afishcangetalongwithalightweightandasimplebonestructure.And2)Limitationstoafish'ssizearepracticallyremoved.Yetthereisonebasicdifficultytolivinginwater---.Forafishtomovethroughwater,itmustactuallyshoveitaside.candothisbywigglingbackandforthin___________motion.Thefishpusheswaterasidebytheforwardmotionofitsheadandwithacurveofitsbodyanditsflexibletail.Nextthewaterflowsbackalongthefish'snarrowingsides,closinginatthetailandhelpingthefishpropelitselfforward.__________________hasliterallythedevelopmentoffish.Aflatandangularcanbemovedthroughwateronlywithdifficulty.,fishhaveabasicthatisbeautifullyadaptedtodealwiththispeculiarity.47.Whatisthetalkmainlyabout?48.Whatdoesthespeakermentionasaproblemthatwaterpresentstofish?49.Thespeakercomparesafish'smovementwiththatofwhatcreature?50.Whataspectofafishdoesthespeakerdiscussinthemostdetail?www.xiaoma.com小马过河新托福备考社区（二）大乌贼王43.(A)Becauseofitssmell.(B)Becauseofitseyes.(C)Becauseofitssize.(D)Becauseofitsbehavior.44.(A)Howseaanimalsmanagetoexist.(B)Howlargeseaanimalscanbe.(C)Howfrighteningthesquidis.(D)Howlittleisknownaboutthesea.45.(A)Whyitisdif