阅读理解Scientiststhinkthattherehasbeenlifeontheearthforhun...
问题详情：阅读理解Scientiststhinkthattherehasbeenlifeontheearthforhundredsofmillionsofyears.However,wehavenotfoundlifeonanyotherplanetsyet.Theearthisaplanetanditgoesaroundthesun,whichisastar.Sevenotherp...