补全对话。（共4小题，每小题1分；计4分）

Li Yang: Good morning. Mathew.

Mathew: Good morning, Li Yang.    小题1:  

Li Yang: There's still smog (雾霾) today. We'll have to go to school with face masks(口罩).

Mathew:    小题2: According to the news, PM2.5 pollution is the main problem with air pollution.

Li Yang: Yes, and air pollution has done harm to people's health.

Mathew: So the Chinese government and Chinese people must take action to fight it.

Li Yang:    小题3:   

Mathew: Yeah. Since PM2.5 is mainly caused by vehicles(机动车)and factories, cars with large

emissions(排放)should not be allowed and factories should be closely watched.

Li Yang: I agree.  小题4:   And we suggest making the blue skies return for good.

Mathew: I hope so, too.

五号字6倍是小五号字的（）倍。

A.9

B.8

C.7.5

D.7