ln the cities,there are a great many people,and there are too many cars running on the road.……
The gas from the car is full of poison.Every day we breathe(呼吸）it in and o___.This makes us feel sick.Because so many cars,there are many f_____,too.They give off(发出）
b______ or grey smoke .This kind of smoke is poisonous,and is harmful(有害的）to our h______.So in order to keep us healthy,we must take a_____ to fight pollution.