Peopleandthesourcesofairpollutionarefoundinthesamep...
問題詳情： Peopleandthesourcesofairpollutionarefoundinthesameplaces.Thismeansthatcitieswithlargepopulationshavethebiggestproblemofdirtyair.Airpollutioniscausedbymanydifferentthings.Amajorsourceof...