the earth is our (home ).we must take care of it .that is to say ,we must k( eep ) theland,air and water clean
mang years ago pullution was not so serious because there not so m( any ) people there was e( nough )clean air ,lang and water when the land or the river was dirty in one place,man moved to a( nother ) place.but now man is slowyly p(olluting ) the whole world and there is not enough clean air or clean lang or clean water remember:more people ,m( ore ) pollution