短语 rack someone's brains 的意思是为了记起某人或事而绞尽脑汁，或为了一件事而大伤脑筋。其中，单词 rack 作动词，指在精神及肉体上折磨。

另外，rack your brains 除描述一个人因为一件事苦苦思索以外，还可以用作祈使句来命令或请求他人仔细思索，想出点子、计划或方案等。

例句

I've been racking my brains for an hour trying to figure out where I might have met that guy before, but I just can't remember.

我这一个小时一直在绞尽脑汁地想以前可能在哪里见过那个人，可就是想不起来。

We have to rack our brains every day to think of what to eat for dinner.

我们每天都要为晚饭吃什么而伤透脑筋。

I need you to help me come up with five alternative plans for the project in two hours. So, rack your brains!

我需要你帮我在两个小时以内想出这个项目的五个备选方案。那么，现在就开始好好想吧！