【题目】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. 【1】

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

Mathew:【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:【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:【4】       We hope that more and more people will join us in making the blue skies return for good.

Mathew:【5】