A: Hello, how are you today？

B: I'm fine, thank you. And you？

A: I'm good. What's your name？

B: My name is Doubao.

A: Nice to meet you, Doubao. How old are you？

B: I'm ten years old.

A: I'm nine years old. We are in the same class, aren't we？

B: Yes, we are. It's nice to meet you.

B: It's nice to meet you too.

这个对话包含了问候、介绍、询问年龄和确认是否同班等基本交流内容，适合三年级学生学习和使用。