2016-2017学年高中英语 Unit 4 Wildlife protection练习试题 新人教版必修2

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1、Unit4　Wildlifeprotection【导语】　专家指出：地球上的动植物物种正以前所未有的速度消失，而无论是它们栖息地的丧失、污染，还是全球变暖带来的间接影响，祸根都源于人类。北部白犀牛　　　小嘴狐猴Extinctionisforever!Asalmosteveryoneknows，tobecomeextinctistobegoneforever.Evenbeforeman'sarrivalonEarth，speciesbecameextinctquitenaturally.Naturalextinctionhappensw

2、henaspeciesdecreasesinnumbersgraduallybutsteadilyattheendofitsevolutionaryperiodonEarth.Thelengthofthisperioddependsonhowwellaspeciescangetusedtochangesaroundit.Thisprocessofextinctioncantakeaverylongtime—sometimesseveralmillionyears—andtheextinctionofonespeciesisimmedi

3、atelyfollowedbytheappearanceofanotherinacontinuouscycle.Thecaseofthedinosaursisthemostwell－knownexampleofnaturalextinction.TheyappearedonEarthabout200millionyearsagoanddominatedbothlandandseaforalmost100millionyears.Itisnotcertainwhythedinosaursbecameextinct，buttheirdis

4、appearancewasanaturaloneandnewspeciesofanimalsevolvedtoreplacethem.Therateofextinctionhasspeededupunnaturallyoverthelast400years，risingsharplysince1990.Thisincreaseintherateofextinctionisdirectlyrelatedtotheincreaseinthehumanpopulationoverthesameperiodoftime.Thegreatnum

5、berofhumanshascausedgreatdamagetotheplanet，aswildhabitatshavebeentakenover，forcinganimalsandplantsintosmallerandsmallerareas，untilsomeofthemhavebecomeextinct.Wehavealsopollutedsomehabitatswithchemicalsandwaste，makingthemunfitforwildlife.Thesecausesofextinctionareknownas

6、indirectdestruction.Animalsmayalsobecomeextinctthroughdirectdestruction.Thisincludesthehuntingandcatchingofanimals.Manhasalwayshuntedandkilledwildlifebutwhenearlyhumanslivedmoreinharmonywithnature，theykilledanimalsforessentialfoodandclothing.Whenfirearmswereinvented，gre

7、atdestructionofspecieswas16possible.Animalshavebeen，andstillare，killedformeat，clothing，medicines，feathers，eggs—andsometimesjustforamusement.Somespeciesarestillcaughtinthewildforthelivepettrade，eventhoughtheirnumbersaredecreasing.Theextinctionofatleast500speciesofanimals

8、hasbeencausedbyman.Todaythereareabout5，000endangeredanimalsandatleastonespeciesdiesouteveryyear.Thereareprobab