四级 四级强化备考阅读练习16.docx
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四级 四级强化备考阅读练习16.docx
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四级四级强化备考阅读练习16
UnitSixteen
Passage1
WhatWillSpacePeopleLookLike?
Onceweareinspace,thequestionarises—willwebetheonlyones?
Willwefindotherintelligentbeingsplying(往返于)thespaceways,andifso,whatwilltheybelike?
Wecannotpredicteverything,ofcourse,butwedohaveagoodideaofwhatspacepeoplemightlooklike.
Supposethatthiseveningaspaceshipfromsomewhereoutsidethesolarsystemlandedunnoticedinyourneighborhood.Supposeyousawthreebeingsfromthatshipwalkdowntheroadinfrontofyourhouseatdusk.Wouldyourunscreamingtothetelephonetocallthepolice?
No,thechancesarethatyouwouldn'tevengivethemasecondlook.
Wecanbealmostcertainthatourvisitorsfromspacewillnothavethreeeyes,webbed(有蹼的)feet,ortelevisionantennaegrowingoutoftheirforeheads.Instead,scientiststheorize,theywillprobablybearastrongresemblancetothemannextdoor.
Thereasonwecanmakethisassumptionisthatsciencehasshownthattheshapeofalivingbodyisnotaccidental.
Therearerulesof"biologicalconstruction"thathelpuspicturepresumedvisitorsbeforetheyactuallystepoutoftheirspaceship.
Inapplyingtherules,wehavetomakejusttwoassumptions.Thefirstisthatthebodiesofspacemenconsistofprotoplasm(原生质)likeours.Thesecondisthattheyareintelligent,whichisaninescapablefactonceweaccepttheideathattheyarecapableofbuildingaspaceship.
Withthoseassumptionsinmind,wecanpaintthisportraitofthemanfromPlanetX.:
Hebreathesair.Waterbreathersmightdevelopsomeintelligence,buttheycouldnotsmelt(熔炼)metalsunderwater.ThismeansthatanydevelopmentabovethelevelofourownStoneAgeistheaccomplishmentofairbreathers.
Heeatsbothplantsandmeat.Astrictplant-eaterspendstoomuchtimestuffinghimselfwithfoodtobuildthekindofcivilizationwhichisnecessarytoproduceaspaceship.Animalswhichcandigestmeatonlywouldnotbelikelytosurvivetheoccasionaladverseperiodswhichverylikelyoccuronallplanetsandwipeoutthelessadaptableformsoflife.
He'sprobablynotmuchlargerthanthelargesthumanbeing.Thelimitingfactorhereissomethingcalledthespare-cubelaw.Ifyoudoubletheheightofa,personwithoutchanginghisproportions,youhaveabeingwithweighttimestheweight.Thismeansthataperson12feettall,forexample,mustbeclumsyandcannotperformprecisionwork.Andprecisionworkwillbeessential,ofcourse,inbuildingthespaceship.
Heweighsatleast40pounds,andprobablymore.Abrainofacertainsizeandcomplexitywouldberequiredforthebuildingofaspaceship.Thebrainofourspacemenwouldweighatleast2pounds.Andfromourstudiesofanimalsonearth,weknowthatabodyweighingatleast40poundsisrequiredtosupporta2-poundbrain.
Hehasaskullofsomekind.Themostvaluableorganofanintelligentbeingishisbrain,andhisbrainmustbeprotectedinsomemanneragainstinjury.
Hehastwoeyesandears.The"three-eyedmanfromspace"isnotaverylikelycreation.Twoeyesarebetterthanoneforthepurposeofjudgingdistanceandshape,butthreewouldnotbebetterthantwo.Thesamegoesforears.Moreeyesandearswouldbeusefulassparesincaseofaccidentsbutearthorganisms,atleast,donotruntospares.Wedonotknowthereasonforthisbutitislogicaltoassumethatlifeonotherplanetswouldnothavedevelopedalongdifferentlines.
Theeyesandearsarenearthebrain.Informationgatheredbyeyesandearsmustreachthebrainquicklyinordertobeuseful.Thistransmissionbythenervesisslow.Thereforethesenseorgansmustbeclosetothebraintoshortenthetimelagbetweeninformationandreaction.
Hehas"hands"and"feet".Weknowthatourspacemenwillwalkerect.Inordertosurvive,anybeingmustbeabletomovearound.Butinordertobuildhewouldneedsomethingresemblingourhands.Somewherealongthelineofhisdevelopmenthewouldhavehadtofreeonepairoflegstoallowthemtobecomehands.Theonlywaytodothisistolearntostand.
Also,itisalmostcertainthatonceonhisbacklegshewoulddevelopbendingfingersandathumb.Toproduceahighstateofdevelopmenthewouldneedtopickupthings,tobeabletograsp,hold,pushandpull.Whynottentacles(触须),suchasonanoctopus?
Becausetentaclescanpullbutcannotpusheffectively.
Nowthatwe'vedrawnaroughportraitoftheManfromPlanetX,isthereanythingwecanguessaboutPlanetXitself?
Hereagaintheanswerisafamiliarone;hisplanetisprobablyverymuchlikeours. Wewouldprobablybeabletoliveonit.
Firstofall,PlanetXcan't
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