rack one's brains

殚精竭虑绞尽脑汁苦思冥想绞尽脑汁地思考

rack one's brains 近义词

rack one's brains

等同于 mull

rack one's brains

等同于 puzzle

rack one's brains

等同于 ruminate

rack one's brains

等同于 think

rack one's brains

等同于 ratiocinate

rack one's brains

等同于 concentrate