[素昧平生, sù mèi píng shēngㄙㄨˋ ㄇㄟˋ ㄆㄧㄥˊ ㄕㄥ] to have never met sb before (成语 saw); entirely unacquainted; a complete stranger; not to know sb from Adam#62922
[夙兴夜寐 / 夙興夜寐, sù xīng yè mèiㄙㄨˋ ㄒㄧㄥ ㄧㄝˋ ㄇㄟˋ] to rise early and sleep late (成语 saw); to work hard; to study diligently; to burn the candle at both ends#159797