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1、2004年5月份托福阅读真题及其答案ReadingQuestion1-10Allmammalsfeedtheiryoung.Belugawhalemothers,forexample,nursetheircalvesforsometwentymonths,untiltheyareabouttogivebirthagainandtheiryoungareabletofindtheirownfood.Thebehavioroffeedingoftheyoungisbuiltintothereproductiv
2、esystem.Itisanonelectivepartofparentalcareandthedefiningfeatureofamammal,themostimportantthingthatmammals--whethermarsupials,platypuses,spinyanteaters,orplacentalmammals--haveincommon.Butnotallanimalparents,eventhosethattendtheiroffspringtothepointofhatch
3、ingorbirth,feedtheiryoung.Mostegg-guardingfishdonot,forthesimplereasonthattheiryoungaresomuchsmallerthantheparentsandeatfoodthatisalsomuchsmallerthanthefoodeatenbyadults.Inreptiles,thecrocodilemotherprotectsheryoungaftertheyhavehatchedandtakesthemdowntoth
4、ewater,wheretheywillfindfood,butshedoesnotactuallyfeedthem.Fewinsectsfeedtheiryoungafterhatching,butsomemakeotherarrangement,provisioningtheircellsandnestswithcaterpillarsandspidersthattheyhaveparalyzedwiththeirvenomandstoredinastateofsuspendedanimationso
5、thattheirlarvaemighthaveasupplyoffreshfoodwhentheyhatch.Foranimalsotherthanmammals,then,feedingisnotintrinsictoparentalcare.Animalsaddittotheirreproductivestrategiestogivethemanedgeintheirlifelongquestfordescendants.Themostvulnerablemomentinanyanimal'slif
6、eiswhenitfirstfindsitselfcompletelyonitsown,whenitmustforageandfendforitself.Feedingpostponesthatmomentuntilayounganimalhasgrowntosuchasizethatitisbetterabletocope.Youngthatarefedbytheirparentsbecomenutritionallyindependentatamuchgreaterfractionoftheirful
7、ladultsize.Andinthemeantimethoseyoungareshieldedagainstthevagariesoffluctuatingofdifficult-to-findsupplies.Onceaspeciesdoestakethestepoffeedingitsyoung,theyoungbecometotallydependentontheextraeffort.Ifbothparentsareremoved,theyounggenerallydonosurvive.1.W
8、hatdoesthepassagemainlydiscuss?A.Thecarethatvariousanimalsgivetotheiroffspring.B.Thedifficultiesyounganimalsfaceinobtainingfood.C.Themethodsthatmammalsusetonursetheiryoung.D.Theimportanceamongyoungmammalsofbecomingi