根据短文选择正确答案。

A: Good morning, Tom.

B: Good morning, John. Where are you from?

A: I'm from America, And you?

B: I'm from London.

A: What's Big Ben like?

B: It's tall and old .

A: Do you know London Bridge?

B: Yes. It's falling down.

A: It's very famous.

B: Yes. Welcome to London.