阅读下面短文，根据上下文填入适当的词语，或使用括号中的词语的适当形式填空，并将答案填写在答题卡上标号为31-40的相应位置。
With the _____________ (develop) of industry, air pollution is getting more _________ more serious. In Beijing, many people suffer different kinds of illnesses because
________ air pollution.
Air pollution is caused by the following ________[ reason]: about half ________ the problem is caused by vehicles. There are more and more cars, buses on the roads, and they give off poisonous gases. 25% of air pollution is caused by factories. Another factor is the smokers.
_________[Smoke] not only does harm to their health but also to others. Besides these, about 10%of air pollution is caused by other reasons.
We should take some measures to fight __________ pollution. New fuel[燃料] can
________[use] to replace[代替] gas. We can plant more trees. ________ everybody realizes the importance of environment and does something to stop pollution, ________ problem will be solved.