殫精竭慮 [ㄉㄢ ㄐㄧㄥ ㄐㄧㄝˊ ㄌㄩˋ; dan1 jing1 jie2 lu:4] to exhaust one's thoughts and ingenuity (idiom); to think sth through thoroughly to rack one's brains to leave no stone unturned ◄ ►