根据上下文补全对话，在横线上写出所缺少的内容。

A: Excuse me. Is there a post office near here? 

B: I'm sorry, I don't know. You can ask this policeman, I think. 

A: 1. ____________________________. Excuse me, sir. I need your help.

C: Are you looking for the nearest post office? 

A: Yes. 

C: 2.__________________________________________________, turn left at the second crossing, and walk

    on to the end. The post office is on the right.

A: 3.________________________________________________________?

C: It's about two kilometers away. You can also take a bus.

A: 4.________________________________________________________?

C: No. 5 bus. The bus stop is over there, on the other side of the street.

A: Thank you very much.

C: 5.________________________________________________________