但这是答非所问。

But this is a simple answer to the wrong question.

她想回答好老师的问题，可她答非所问。

She tried to answer the teacher's question, but she was way out in left field.

她想回答好老师的问题，可她 答非所问 。

This is what I think although not quite an answer to your question.

那老僧既聋且昏， 又齿落舌钝， 所答非所问。

The man proved to be deaf as well as dim-witted, for his mumbled answers were quite irrelevant.

他好像不满意，说我答非所问，没有雄心大志，这对做买卖是很糟糕的。

He looked upset and told me that I always evaded the question and that I had no ambition, which was disastrous in the business world.