Don't work too hard. You need to conserve/save your strength for tomorrow.干活别太卖劲，你要为明天保存体力。Mrs Mueller reminded her that she should conserve her strength.米勒夫人提醒她说，她应该保存体力。The runners saved their energy for the last lap. = The runners saved themselves for the last lap.运动员为最后一圈保存体力。