_2011年职称英语冲刺班课件第13讲-理工类

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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.Withoutsuchproblems,animalsinzoosshouldlivetoaripeoldage1

2、.Butthatmaynotbetruefor2thelargestlandanimalsonEarth.Scientistshaveknownthatelephantsinzoosoftensufferfrompoorhealth.Theydevelopdiseases,jointproblemsandbehaviorchanges.Sometimes,theyevenbecomeinfertile,orunabletohavebabies.Tolearnmoreabouthowcaptivityaffectselephants,ateamofinternationalscientists

3、comparedthelifespansoffemaleelephantsborninzooswithfemaleelephantslivingoutdoorsintheirnativelands.Zooskeepdetailedrecordsofalltheanimalsintheircare,documentingfactorssuchasbirthdates,illnesses,weightanddeath.Theserecordsmadeitpossiblefortheresearcherstoanalyze40yearsofdataon800AfricanandAsianeleph

4、antsinzoosacrossEurope.Thescientistscomparedthelifespansofthezoo-bornelephantswiththelifespansofthousandsoffemalewildelephantsinAfricaandAsianelephantsthatworkinloggingcamps3,overapproximatelythesametimeperiod.TheteamfoundthatfemaleAfricanelephantsborninzooslivedanaverageof16.9years.Theirwildcounte

5、rpartswhodiedofnaturalcauseslivedanaverageof56years--morethenthreetimesaslong.FemaleAsianelephantsfollowedasimilarpattern.Inzoos,theylived18.9years,whilethoseintheloggingcampslived41.7years.Scientistsdon'tyetknowwhywildelephantsseemtofaresomuchbetterthantheirzoo-raisedcounterparts.GeorgiaMason,abio

6、logistattheUniversityofGuelphinCanadawholedstudy,thinksstressandobesitymaybetoblame4.Zooelephantsdon'tgetthesamekindofexercisetheywouldinthewild,andmostareveryfat.Elephantsociallivesarealsomuchdifferentinzoosthaninthewild,wheretheyliveinlargeherdsandfamilygroups.大家论坛职称英语http://club.topsage.com/foru

7、m-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