I don't know whether you have ever seen a map of a person's mind.

我不知道你们是否见过一个人的大脑图。

youdao

I don't know what is on his mind; he always looks restless.

不知他有什么事，老是心神不定的样子。

《新英汉大辞典》

I don't know what lurks in his mind.

我不知道他心里潜藏着什么。

youdao

You know, it's like three dollars for something that's, I don't know, in my mind pretty luxurious."

VOA: special.2010.04.12

We don't know what Plato had in mind.

不知道柏拉图是怎么想的。

耶鲁公开课 - 死亡课程节选

- I don't know if you...- It'll give your old man some peace of mind.

VOA: standard.other

"I'm sure what was going through the president's mind is, we really don't know who did this, " Axelrod said on Tuesday morning.

WSJ: Is it 'terrorism'? Anatomy of a very murky word

And officials say they don't really know what exactly they had in mind.

NPR: German Officials Look for Others in Terror Plot

I've got in mind a figure of 6 years, but I don't know where I've got that from.

BBC: Money Box - Saturday 30 December 2000