Unit4WarmingUp&Reading阅读理解ATheearthistheonlyplanetthatscientiststhinkhaslife
Whydoestheearthhavelifewhiletheotherplanetsdon’t
Foronething,theearthisjusttherighttemperature
Asthethirdplanetfromthesun,theearthseemstobejusttherightdistanceaway
Theplanetswhichareclosertothesunaresohotthattheirsurfacesbake(烘烤)inthesun
Thefarthestplanetsarecoldballs
Whentheearthdeveloped—whichscientistsbelievemayhavehappenedabout4billionyearsago—manygasescoveredtheearth
Thegasescausedtheearthtobehot
Butsomethingwonderfulhappened
Thetemperaturewasjustrightforthickcloudstoform
Itrainedveryhardforaverylongtime
Thisgavetheearthitsoceans
Watermadeitpossibleforplantstogrow
Theplantscreatedoxygenintheatmosphere
Oxygenisthegasthathumansandanimalsbreathe
Onlyoneotherplanetinthesolarsystemseemstobesomethingliketheearth