Evenbeforetherewerepeople,therewerecasesofairpollution....
问题详情：Evenbeforetherewerepeople,therewerecasesofairpollution.Therewereduststorms(沙尘暴).Volcanoeserupted,sendingashandpoisonousgasesintotheatmosphere.Whenpeopleappearedonthescene(登上历史舞台)andbe...