2024_2025年新教材高中英语Unit3CONSERVTIONSectionⅡLESSON1THESIXTHEXTINCTION学案北师大版选择性必修第一册.doc

PAGE

PAGE13

LESSON1THESIXTHEXTINCTION

eq\a\vs4\al([原文呈现])

Extinctions,whereentirespecies①arewiped②out,arenotunusual③inourEarth’shistory.Infact,over90percentofallspeciesthateverlivedarenowextinct.Inthelast500millionyears,therehavebeenfivetimeswhenlifeonEarthhasalmostended.Theseincludethethirdmass④extinction,knownasthe“GreatDying”，whichkilled90%to96%ofallspecies.Andthefifthevent,whichoccurred66millionyearsago,causedthedeathofthedinosaurs.Thereasonsforextinctionsarevaried⑤.Accordingtoscientists,theyincludevolcaniceruptions,asteroids⑥hittingtheEarthfromspace,changesinsealevels,thedecrease⑦oftheoxygencontentoftheseaandglobalwarming.ManyscientistssaywearenowenteringtheEarth’ssixthmassextinction.Thistime,humanactivitywillbetoblame⑧.

Althoughitisnotunusualforspeciestodieout⑨naturally,therateatwhichthisisnowhappeningiscauseforconcern.A2015studybyscientistswhowerebasedatBrownUniversityandDukeUniversityintheUS,lookedathowquicklyspeciesdieoutduetonaturalcauses,thatis,the“backgroundextinctionrate”.Theyfoundthathumanactivityiscausingspeciestodieout1,000timesfasterthannormal.(1)Thereisalonglistofreasonswhysomanyspeciesaredyingout:airandwaterpollution,forestsbeingdestroyed,factoryfarmingandoverfishing.Itisclearthathumanactivityhasnegativelyaffected⑩allotherspeciesonEarth,includinganimalsandplants.

(1)本句是一个主从复合句。句中that引导宾语从句；1,000timesfaster是倍数的表示方法。

Ifasixthmassextinctionoccurs,scientistswhohavestudiedtheissuebelievethatupto?threequartersofallspeciesonEarthcoulddieout.Ofcourse,aswehumansdependon?somanyspeciesforoursurvival,wewouldalsobeatrisk?ofdyingout.Ourworldandourlivesdependonthebalanceinnaturebetweenanimalsandplants.Withoutforests,wewouldhavenoairt