根据对话内容，从方框中所给的七个选项中选出五个句子补全对话，使对话完整、通顺。并将所选标号在对话后面的横线上。
Li Yang: Good morning, Mathew.
Mathew:  Good morning, Li Yang.         
Li Yang: There's still smog（雾霾）today. We'll have to go to school with face masks（口罩）．
Mathew:           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.
Ji Yang:           
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.
Li Yang:       We hope that more and more people will join us in making the blue skies return for good.
Mathew:          

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