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1、LongerLivesforWildElephants（一）2011年理工类B级真题Mostpeoplethinkofzoosassafeplacesforanimals,wherestrugglessuchashavingdifficultyfindingfoodandavoidingpredators（猛兽）don’texist.Withoutsuchproblems,animalsinzoosshouldlivetoaripe（成熟的）oldage.ButthatmaynotbetrueforthelargestlandanimalsonE
2、arth.Scientistshaveknownthatelephantsinzoosoftensufferfrompoorhealth.Sometimes,theyevenbecomeunabletohavebabies.Tolearnmoreabouthowcaptivity（圈养）affectselephants,ateamofinternationalscientistscomparedthelifespansoffemaleelephantsborninzooswithfemaleelephantslivingoutdoorsinthe
3、irnativelands.Zooskeepdetailedrecordsofalltheanimalsintheircare,documentingfactorssuchasbirthdates,illnesses,weightanddeath.Theserecordsmadeitpossiblefortheresearcherstoanalyze40yearsofdataon800AfricanandAsianelephantsinzoosacrossEurope.Thescientistscomparedthelifespansofthez
4、oo-bornfemaleelephantswiththelifespansofthousandsofwildfemaleelephantsinAfricaandAsianelephantsthatworkinloggingcamps（伐木场）,overapproximatelythesametimeperiod.TheteamfoundthatfemaleAfricanelephantsborninzooslivedanaverageof16.9years.Theirwildcounterpartswhodiedofnaturalcausesl
5、ivedanaverageof56years—morethanthreetimesaslong.FemaleAsianelephantsfollowedasimilarpattern.Inzoos,theylived18.9years,whilethoseintheloggingcampslived41.7years.Scientistsdon’tknowyetwhywildelephantsseemtogetonsomuchbetterthantheirzoo-raisedcounterparts.GeorgiaMason,abiologist
6、attheUniversityofGuelphinCanadawholedthestudy,thinksstressandobesity（肥胖症）maybetoblame.Zooelephantsdon'tgetthesamekindofexercisetheywouldinthewild,andmostareveryfat.Sociallivesofelephantsarcalsomuchdifferentinzoosthaninthewild,wheretheyliveinlargeherdsandfamilygroups.Thestudyr
7、aisessomequestionsaboutacquiringmoreelephantstokeepinzoos.Whilesomethreatenedandendangeredspecieslivinginzoosreproduce（生殖）successfullyandmaintainhealthypopulations,thatdoesn'tappeartobethecasewithelephants.41．Unlikeotheranimalsinzoos,zoo-raisedelephants________.A．livealonglif
8、e.B．givebirthtomanybabies.C．developpoorhealth.D．havedifficultygettin
