读一读，选择合适的句子补全对话。

A. Thank you. B. What's this? C. How are you? D. Good morning, E. It's a chair.

A：Good morning, Lingling.

B： Ms. Smart.

A：

B：I'm fine, thank you.

A：

B：It's a desk.

A：What's that?

B：

A：Sit down, please, Lingling.

B：