When we read newspapers， we often come across the word This word was not familiar to the people some decades But now， it is a serious threat to us it means the poisoning of the air， seas， rivers and lands， which would do harm to our There are many factories that bring pollution to We can not have fresh air in the This is mainly because of the poisonous smoke coming from factories， especially chemical In rivers， seas and oceans， there are industrial Some factories just throw their wastes into seas or let them flow into When people drink the water from such rivers， they get Besides， there is rubbish from ships and when sometimes an accident occurs in an ocean， oil flows out from On land， the accumulation of rubbish in the streets may dirty the city and ruin our This is mainly due to the improper disposal of rubbish by
