其實英文有很多成語，其中有 （to have something) in mind 、on my mind 這兩個，用法根本不同， We say "do you have something in mind" to ask if someone has a particular idea (他們有沒有意見） Where as, if something is "on your mind", it means you are thinking about it, 就是說，正在考慮這件事。 （尋思？思謀？） I hope that helps “在我的腦海裡” 這句話，你們平常怎麼用？ 謝謝

If you mean you are thinking about English then it is on my mind :)