根据下面的对话情景，在每个空白处填上一个适当的句子，使对话的意思连贯、完整。

A: Tom, long time no see. ?

B: I went to Tibet with my parents for the summer vacation.

A: Wow, how was your trip?

B:. Blue sky, white clouds and fresh air made me feel comfortable and relaxed. How about you?

A: .

B: Really? You must have had a great time with your friends.

A: Oh, no. We didn't enjoy ourselves. We saw litter everywhere on the West Hill.

B: What a pity! I think we should do something to protect the West Hill

A: You're right. ?

B: Sounds great. We can call on more friends to help us.

A: Good idea. Shall we start it tomorrow?

B: Yes. ?

A: Let's meet at the school gate at 8:30.

B: OK. See you.