Common errors
Syntactic errors
Learners might incorrectly add the question particle 吗/嗎 at the end of the question.
*你去哪儿吗?
你去哪儿?
*你去哪兒嗎?
你去哪兒?
Lexical errors
Learners might use the demonstrative pronoun instead of the interrogative one. A question with a demonstrative pronoun in the example below is also acceptable (if used with a rising intonation), but has a different meaning.
你昨天去哪儿了?
你昨天去哪兒了 ?
Where did you go yesterday?
你昨天去那儿了?
你昨天去那兒了?
Did you go there yesterday?
Learners might use an interrogative pronoun 哪 instead of 哪儿/哪兒 / 哪里/哪裡.
*你在哪工作?
你在哪儿工作?
*你在哪工作?
你在哪兒工作?