With the development of industry，air pollution is getting more and more serious. In Shanghai, many people suffer from different kinds of illnesses because    air pollution.
Air pollution is  (main) caused by the following reasons. About half of the problem is caused by vehicles(交通工具). There are more and more cars and buses on the road,   give off    (poison) gases. 35% of air pollution is caused by factories. factor is smoking.    (smoke) does harm to others’ health as well as to __ of the smokers. Besides, about 10% of air pollution is caused by other reasons. We should take some measures to fight against pollution. New fuel can be used to take _  place of gas. We can plant more trees，grass and flowers. All in all, if everybody realizes the  (important) of environment and does something to stop pollution, the problem   (solve).