阅读下面对话，从方框中选择五个最适当的句子完成对话（其中有2个选项是多余的）。
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.
LiYang:  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.
Ji Yang:小题3:
Mathew:  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.
LiYang:小题4:       We hope that more and more people will join us in making the blue skies return for good.
Mathew:小题5:

A. I hope so, too. B. Can you give any advice? C. I don't think so. D. What a pityl E. I agree. F. What's the weather like today? G. That's OK.