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.
小题1:A
小题2:C
小题3:B
小题4:D
题目分析：
小题1:根据下面应答语There's still smog (雾霾) today可知此处是在询问今天的天气情况，所以选 A。
小题2:根据上句There's still smog (雾霾) today. We'll have to go to school with face masks(口罩).和下句According to the news, PM2.5 pollution is the main problem with air pollution 可知选C，真遗憾！
小题3:根据答语Yeah.可知此处该是个一般问句，所以选B。
小题4:根据下句And we suggest making the blue skies return for good.可推知该句是说我们希望越来越多的人加入我们的行列，所以选D。