四级 四级强化备考阅读练习16Word下载.docx

四级 四级强化备考阅读练习16Word下载.docx

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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