有人认为这可能是恐龙灭绝的原因如果是这样那么未来课件.ppt

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1、导读：据研究,6500万年前的小行星撞击地球，对地球造成了几乎是毁灭性的破坏，有人认为这可能是恐龙灭绝的原因。如果是这样，那么未来再有这样的小行星或彗星撞击地球，会不会导致人类的毁灭呢？It'ssaidthatahugeasteroid(小行星)smashed(撞击)intotheearth65millionyearsago,whichcertainlysenttheearth'secosystem(生态系统)intoadisasterwhichtookthousandsofyearstorecov

2、erfrom.Scientistssaythatit'sprobablethatsuchdisastercouldhappenagain.Asteroidsarerockybodieswhichtendtoliveinorbits(轨道)betweenMarsandJupiter.Comets,ontheotherhand,areamixofrockandice,andtheycanswingintotheearth'sorbitfromanywhereintheSolarSystem.Comets

3、haveanicytailwhichreflectsthesunandcanthereforebeseenfromtheearth.Butasteroidshavefarlessvisibility(可见度)andhavetobeatleasthalfakilometreacrosstobefound.Therearemillionsofsuchrockyandicybodiesouttherewhichhavenotbeendiscoveredyet.Butdidanasteroidkillthe

4、dinosaurs—andcouldanotherkillus?Despitewhatyoumayhaveheard,ithasn'tbeenprovedthatthehittingwastheonlyreasonforthedinosaurs'dyingout.Buttheasteroidwhichcreatedthehittingwouldcertainlyhavehadagreateffectontheenvironment,andamassextinction(灭绝)didtakeplace

5、aroundthetime.Sofarwehavenoideawhenthenextonewillbebecausewehaven'tspottedityetandnotmanyorganizationsarespendingmoneyonasteroid－detection,becauseadeathlyhittingissuchafarawaypossibility.请根据语义及提示写出单词1.Thereisafriendly__________(氛围)ofhelpingeachotherwit

6、hdifficultiesinstudyinourclass.2.MostofthestudentsinChinabenefitfromtheneweducational__________(体制).3.Shelistenedwitha__________(困惑的)expressiononherface.4.Ibelievehiswordswilldo__________(危害)toourcompany.5.Thewarmspringwindbrushourfaces__________(轻柔地).

7、6.Nothingcan__________(阻止)himdoingresearchintotheissueofwaterpollution.7.Theresultsofthetestarevery__________(令人振奋).8.Health__________(依赖于)upongoodfood,freshairandenoughsleep.atmosphere2.system3.puzzled4.harm5.gently6.prevent7.cheering8.depends9.existe

8、nce10.develop9.Intheopinionofsomephilosophers,everythingin__________(exist)isreasonable.10.Thebestmethodofteaching,Ithink,isto__________(启迪)themindofstudents.请根据语义写出短语1.__________system太阳系2.__________time及时，最终3.__________birthto生(孩子)4._