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英语流利说1L4——U2——1/4listeningEarthformsandextinctionA1.Theearthwasformedaboutfourpointsixbillion(46亿)yearsago.2.Thefirstlifeappearedaboutabillion(10亿)yearslater.3.Thefirstplant-likedidn’tappearuntilaroundtwobillion(20亿)yearsago.4.Untilaboutfivehundredeightymillion(五亿八千万)yearsagolifeformsweresmallandmicroscopic(极小的，微小的).5.Sincethattime,lifehasevolved(进化)intomanydifferenttypesorspecies.6.Howeverscientistsestimate(估计)thatmorethanninetyninepercent（99%）ofthemarenowextinct(灭绝的).B1.Therehavebeenseveralextinction(绝种)eventsinthehistoryoftheearth.2.Inanextinctioneventsmanylifeformsorspeciesoflifedieout.3.Thecausesofmassextinctioneventsareunsolvedmysteries(未解之谜).4.Theseeventsarenotpredictable(预告)andcanhappenatanytime.5.Scientiststhinkthatsomeofthemwerestartedbyasteroidimpacts(影响，碰击或者装机)orvolcaniceruptions(火山爆发).6.Eventslikethis,canchangetheglobalconditionsthatlifedependson.C英语流利说21.Onemajorextinctioneventhappenedaboutsixty-sixmillion(6600万)yearsago.2.Thateventmayhavebeenstartedbyalargeasteroidthathittheearth.3.Asaresult,thedinosaursandabouthalfofallspecies(物种，种类，类型)ontheplanetdieout.4.Whentheasteroidshittheearth,itstartedachainofevents.5.Achainofeventsisaseriesofeventslinkedtogetherlikeachain.D1.Thisparticularchainofeventshappenedoveraperiodofmonthsandyears.2.Whentheasteroidhittheearth,itcausedahugecloudofdusttoentertheatmosphere.3.ThiscloudofdustblockedtheSunanddarkenedtheEarthformanymonths.4.Withoutenoughsunlight,plantsandplant-eatinganimalsquicklydied.5.Withthedeathsofsomanyplantsandanimals,thefoodchaincollapsed.6.Thisledtothedeathsofmanymorespecies.E1.Massextinctioneventshaveplayedanimportantpartintheevolution(演变，发生，进化论)oflife.2.Infact,someextinctioneventshavehelpedtoaccelerate(加快，加速)evolution.英语流利说33.Forexample,somemammals(哺乳动物)livedthroughtheageofthedinosaurs,buttheycouldn’tcompete(竞争).4.Whenthedinosaurswereremoved,themammalswereabletocompetemoresuccessfully.5.Oncetheycouldcompete,mammalsevolvedtoahigherstate.6.Withoutextinctionevents,perhapswewouldn’tbeheretoday.Existence(存在)F1.Scientistsestimate(估计，预测)thattherehavebeenatleastfivemassextinctions(五次大灭绝)inthelastfivehundredfortymillionyears.2.Theyalsobelievethatwehaveenteredanewextinctionevents.3.Speciesarebecomingextinctatamuchfasterratethanbefore.4.Insteadofasteroidsorvolcaniceruptionsthecurrent(最近的)eventsistheresultofhumanactivities.5.Humanactivitiesforexamplehaveledtoglobalwarming.G1.globalwarmingistheresultofanincreaseincarbongases(含碳气体)inouratmosphere.2.Thesegasestrapheat(阻碍热量排放)fromthesun,sotheEarthisgettingwarmer.3.Asaresult,sealevelsarerisingandweatherpatterns(气候模式)arechanging.4.Inaddition(另外),wehumansaredestroyingthehabitats(动物的栖息地)ofmanyplantsandanimals.英语流利说45.Cuttingdownforestsandpollutingriversdestroythehabitatsofmanyformsoflife.H1.Thereisnolongeranydoubtthatthisishappening.2.Species(物种，类型)oflifearedisappearingatanincreasingrate.3.Globaltemperaturesarerisingandweatherpatternsarechanging.4.Scientistsarewarningusthatfastactionisnecessarytosaveourfuture.5.Ifwedon’tact,wemaygothewayofthedinosaurs.练：1.(读)thisnewextinctioneventiscausedbyhumans.2.It’swhenanasteroidcollideswithsomething.3.AnasteroidhittheEarthandstartedachainofevents.4.Withtheriseintemperature.Thepolaricecapsaremelting.L4——U2——1/4vocabularyBodyorgan2andhumanbeingevolution(进化)A1.Thebody’scirculatory(循环的)systemincludestheheartandbloodvessels(血管).2.Theheartpumpsbloodtoallpartsofthebodythroughanetwork(网络，网状物)ofarteries(动脉)andveins(静脉).3.Thedigestsystem(消化系统)breaksdown(分解)andabsorbed(吸收)foodintothebody.4.Itsuppliestheenergythatthebodyneedsforgrowthandrepair.英语流利说55.Afterdigestion,excess(超重，超量)foodisturnedintowasteandeliminated(排除，消除)fromthebody.6.Thenervoussystemsincludethebrain,spinal(脊柱的)cord(脊髓)andnerves.7.Thisisyourbodiescontrolsystem.8.Itcontrolsyourmuscles(肌肉)andorgans(器官)includingyourcirculatory(循环)anddigest(消化)system.9.Therespiratory(呼吸的)systemincludesthenoseandlungs.10.Itbringsairandoxygenintothebodyandremovescarbondioxide(二氧化碳).11.Thelungsarewhereoxygenentersthebloodstream(血流，体内循环的血液)and(二氧化碳)carbondioxide(二氧化物)isremoved.12.Theimmune(免疫的)systemprotectsthebodyagainstinfections(传染，感染，传染病)anddiseases.13.Sneezing(打喷嚏)andfeverareexampleofhowtheimmunesystemworks.14.Ifaninfectioninvades(侵入)thebodytheimmunesystemattacks(攻击)it.练：1.Thebloodvessels(血管)thatcarryoxygen-richbloodfromtheheartarecalledarteries(动脉).2.Thenervoussystemregulates(控制，管理，调节)yourheartbeatanddigestion.3.Forsomediseases,theimmunesystemuseswhitebloodcellsandantibodies(抗体)toattackit.4.Thedigestsystemiswherefoodisbrokendownandabsorbedintothebody.英语流利说6B1.Thecontrolleduseoffireallowedpeopletocookfoodandsurviveincolderclimates.2.Fireprovidedlightsothatpeoplecouldworkandsocializeforlongerhours.3.Withtheinventionofagriculture(农耕，农业)peoplecouldgrowfoodinsettleintocommunities.4.Bygrowingfood,peoplecanspendlesstimehunting(打猎)andmoretimeforotherthings,suchasart.5.Thedomestic(家庭的，家的，国内的，驯养的)actionofanimalsallowedpeopletoraiseanduseanimalsforfoodandwork.6.Byraisingherds(放牧)ofanimalssuchassheep,humanshadaregularsupplyofmeatandclothing.7.Thestre