选出合适的句子补全对话。

A. Did you go there? B. Can you tell me more about it? C. What's this? D. Do you know it? E. How long is it?

A: Hello! Simon.

B: It's a stamp about the Great Wall.

A: Yes, it is very famous. And I want to visit it someday.

B: Yes, it is in the north of China. And it is very long.

A:

B: It's about six thousand seven hundred kilometres.

A:

B: Yes, I went there last year.