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1、大家论坛职称英语http://club.topsage.com/forum-109-1.html大家论坛职称英语版块：http://club.topsage.com/forum-109-1.htmlLongerLivesforWildElephantsMostpeoplethinkofzoosassafeplacesforanimals,wherestrugglessuchasdifficultyfindingfoodandavoidingpredatorsdon'texist.Withoutsuch
2、problems,animalsinzoosshouldlivetoaripeoldage1.Butthatmaynotbetruefor2thelargestlandanimalsonEarth.Scientistshaveknownthatelephantsinzoosoftensufferfrompoorhealth.Theydevelopdiseases,jointproblemsandbehaviorchanges.Sometimes,theyevenbecomeinfertile,orun
3、abletohavebabies.Tolearnmoreabouthowcaptivityaffectselephants,ateamofinternationalscientistscomparedthelifespansoffemaleelephantsborninzooswithfemaleelephantslivingoutdoorsintheirnativelands.Zooskeepdetailedrecordsofalltheanimalsintheircare,documentingf
4、actorssuchasbirthdates,illnesses,weightanddeath.Theserecordsmadeitpossiblefortheresearcherstoanalyze40yearsofdataon800AfricanandAsianelephantsinzoosacrossEurope.Thescientistscomparedthelifespansofthezoo-bornelephantswiththelifespansofthousandsoffemalewi
5、ldelephantsinAfricaandAsianelephantsthatworkinloggingcamps3,overapproximatelythesametimeperiod.TheteamfoundthatfemaleAfricanelephantsborninzooslivedanaverageof16.9years.Theirwildcounterpartswhodiedofnaturalcauseslivedanaverageof56years--morethenthreetim
6、esaslong.FemaleAsianelephantsfollowedasimilarpattern.Inzoos,theylived18.9years,whilethoseintheloggingcampslived41.7years.Scientistsdon'tyetknowwhywildelephantsseemtofaresomuchbetterthantheirzoo-raisedcounterparts.GeorgiaMason,abiologistattheUniversityof
7、GuelphinCanadawholedstudy,thinksstressandobesitymaybetoblame4.Zooelephantsdon'tgetthesamekindofexercisetheywouldinthewild,andmostareveryfat.Elephantsociallivesarealsomuchdifferentinzoosthaninthewild,wheretheyliveinlargeherdsandfamilygroups.大家论坛职称英语http:
8、//club.topsage.com/forum-109-1.html大家论坛2011年职称英语考试精华资料大家论坛职称英语版块推荐：http://club.topsage.com/forum-109-1.html2011年幺建华职称英语基础班+精讲班+押题班1月5日正式开始发布2011年职称英语教材新增文章word汇总下载（更新完毕）2011年职称英语综合、理工、卫生类教材及教辅电子书下载2011年职称英语精华资料推荐下载汇总(教材+真题+课件)201
