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.
