从方框中选择合适的选项将对话补充完整。

A. I'm nine years old. B. I'm fine, thank you. C. How are you? D. Good morning. E. Great!

Sarah: Good morning, Chen Jie!

Chen:

Sarah: How are you?

Chen:  

Sarah: Very well, thanks.

Chen: Today is my birthday. Let's eat the cake!

Sarah: Happy birthday! How old are you?

Chen: