江西省萍乡市芦溪中学人教版高中英语必修三学案Unit4第一课时精读课练案

2.According toProfessor Kraemer,the majorproblem in cloning pandaswould bethe lackofA.available pandaeggsB.host animalsC.qualified researchersD.enough money

3.The besttitle forthe passagemay be.A.Chinas Successin PandasCloningB.The FirstCloned Pandain theWorldC.Exploring thePossibility toClone Pandas一D.China theNative Placeof PandasForever

4.From thepassage weknow that.A.Kraemer andhis teamhave succeededincloninga dogB.scientists tryto implanta pandasegg intoa rabbitC.Kraemer willwork withChinese scientistsin cloneresearches二.阅读表达D.about twothousand ofspecies willprobably dieout ina century阅读下面短文，并根据短文后的要求答题A disasterheading ourwayIts saidthat ahuge asteroidsmashed into the earth65million yearsago,which certainlysent theearthsecosystem intoa disasterwhich tookthousands ofyears torecover from.Scientists saythat itsprobablethat suchdisaster couldhappen again.（小彳亍星）Asteroids arerocky bodieswhich tendto livein orbitsbetween Marsand Jupiter.（轨道）Comets,on theother hand,are amix ofrock andice,and theycan swingintotheearths orbitfromanywhere inthe SolarSystem.Comets havean ytail whichreflects thesun andcan thereforebe seen（可见度）from theearth.But asteroidshave farless visibilityand haveto beat leasthalf akilometreacross tobe found.There aremillions ofsuch rockyand icybodies outthere whichhave notbeendiscovered yet.But didan asteroidkill thedinosaurs—and couldanother killusDespite whatyou mayhave heard,it hasntbeen provedthat thehitting wasthe onlyreason fbrthedinosaurs5dying out.But theasteroid whichcreated thehitting wouldcertainly havehad agreat effecton（灭绝）the environment,and amass extinctiondid takeplace aroundthe time.So farwe haveno ideawhen thenext onewill bebecause wehavent spottedit yetand notmanyorganizations arespending moneyon asteroid-detection,because adeathly hittingis sucha farawaypossibility.

1.What isthe differencebetween cometsand asteroids

2.Has asteroid-detection beenwell developedso far。