补全对话。每空一词。

Dave: Hi, Mona! I am going to have a birthday . I want to have it on Saturday evening. Can you come?

Mona: Oh, I am going to   my grandfather on Saturday evening.

Dave: What about Sunday?

Mona: I have to take the piano lessons.

Dave: Oh! When are you  then?

Mona: Well, Friday is fine.

Dave: Friday? That's tomorrow! OK. We can have it then. Can you ask Ali to us?

Mona: Sure. When and where shall we meet?

Dave: Near our school gate at half  four.

Mona: Great! See you then!

Dave: Bye!