题目内容：

People usually check whether their keys, wallets and phones are with them before going out. But many people in China now have one more important thing to take, a face mask. They hope that it can protect them from polluted air.

Since January 2013, many cities in China have seen a lot of foggy days. In Beijing, only five days in January were free of smog (雾霾). What’s the difference between fog and smog?

According to scientists, fog is made up of tiny (微小的) drops of water and also ice particles (颗粒) during very cold conditions. Smog is dirty air that looks like a mixture of smoke and fog, caused mainly by smoke from cars and factories in cities.

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

According to the Chinese Academy of Sciences, two main factors that cause PM 2.5 are motor vehicles and the burning of coal.

Poor air has done harm to people’s health. Children and the elderly are more at risk. A report from Beijing Children’s Hospital shows that from December 5 to December 11, 2013, half of the patients in the hospital came for respiratory (呼吸道的) problems.

Air problems and environmental protection have become a care for the whole nation.

Premier Li Keqiang made his last Government Work Report(政府工作报告) on March 6, 2014. The report said that the government should work hard to prevent pollution and give people a healthy living environment.

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

‘We should give people hope through our actions,’ Li said.

1.The underlined phrase “were free of” means _______________.

A. had some   B. had no

C. had many   D. had more and more

2.According to the third paragraph, we can know that________________.

A. fog is made up of drops of water with smoke

B. smog is formed (形成) during cold hours

C. smog is a mixture of fog and smoke

D. smoke from cars and factories cause fog

3. Paragraphs 4 and 5 are mainly about ________________.

A. what PM 2.5 is and how to protect ourselves against PM 2.5

B. how to prevent PM 2.5 pollution and how PM 2.5 looks

C. what PM 2.5 is and what causes PM 2.5

D. how seriously PM 2.5 affects us and how to deal with PM 2.5

4.From Li Keqiang’s report, we learn that __________________.

A. the environment has improved a lot since Li was in office

B. many people have breathing problems because of the air pollution

C. the air pollution problem is the government’s task

D. the government will try its best to solve the air pollution problem