Why are you smiling?

你为什么在微笑?
玛丽：你为什么在微笑?
托尼：我正想到上学的事。
玛丽：为什么那会让你笑了起来呢?
托尼：因为明天不上学。
玛丽：哦，我明白了。
托尼：现在你也在笑了!

Why are you smiling?

I'm thinking about school.

Why does that make you smiling?

Because there's no school tomorrow

Oh,i see.

You are smiling ,too