题目内容：

根据下面短文内容，在短文的空格处填上一个恰当的词，使短文完整、通顺。

People usually check whether their keys, wallets and phones are with them___1.___ going out. But many people in Chain now have one more important thing to take, a face mask(面罩). They hope that it ___2.____ protect them from polluted air.

Since January, many cities in China have seen a lot of hazy(雾蒙蒙的)days. In Beijing, ____3.___five days in January were free of smog(雾霾). People in Xi’an only saw a blue sky on one day in February. Smog is dirty air that ___4.___like fog and smoke.

An official for the Ministry of Environmental Protection told Beijing News that PM2.5 pollution is the main problem with air pollution. PM2.5 refers to pollution with small particles(颗粒) of 2.5 micrometers(微米) or less in diameter(直径).

According to the Chinese Academy of Sciences, ___5._____cars and burning coal(煤) are two major factors(原因) for PM2,5.

Poor air is___6.___ for people’s health, especially for children and the elderly. A report from Beijing Children’s Hospital shows that from Jan 5 to 11, half of the patients in the internal medicine department(内科门诊) are there for respiratory(呼吸) problems.

Air problems and environmental protection have become a concern(关切的事) for the whole nation. Premier Wen Jiabao___7.___ his last Government Work Report on March 5. the report said that the government should work hard to prevent pollution and give people a ___8.____living environment.

It calls on people to make full use of energy and resources and cut down on energy use.