根据对话内容，在每个空白处填入一个恰当的句子使对话完整、合乎情境。

A: Hello Sandy This is Mary speaking, ？

B. I'm Xi'an

A. Are you taking a holiday there?

B. Yes.  ？

A: I'm writing a report.

B: ?

A: It's about the population.

B: Well, I think you can write about the population of Xi' an.

A: Good idea. ?

B: More than 8 million.

A: Is the population of Xi'an larger than that of Dalian?

B: Let me ask my father. Maybe he knows it.

A: All right.