根据对话内容，在空白处填写适当的话语，使对话完整、正确。

A: Hi, Linda!

B: Hi, Michael!

A: bad weather! There is so much sand in the air.

B: So it is. when the sandstorm (沙尘暴) came?

A: I was waiting for the bus. There was lots of sand flying in the air when the wind was blowing strongly. So I couldn't see anything clearly outside.

B: But do you know what causes these sandstorms?

A: People do something bad, such as cutting down too many trees.

B: . I think we need to work hard to protect (保护) our environment.

A: I agree with you. We must protect our home —the earth.

B: make notices?

A: Good idea. Let's on weekends.

B: Then everyone will know how to protect our earth.