Nǐ láizì nǎɡe chénɡshì？

你来自哪个城市？

Which city are you from?

Notes:

你(nǐ): you

来自(láizì): come from

哪个(nǎɡe): which one

城市(chénɡshì): city

Example:

A：你来自哪个城市？

     Nǐ láizì nǎɡe chénɡshì？

     Which city are you from?

B：北京。

     Běijīnɡ.

     Beijing.