根据上下文，补全对话

A: Feel free to ask me anything about the rivers in China.

B:

A: Ah, it's the Yangtze River.

B:

A: It's about 6,300 kilometers long.

B: Is it also the longest one in the world?

A: No.

B: What about the Yellow River?

A:

B: Oh, do you know how long it is?

A: