One man's fault is other man's lesson.前车之鉴。

One man's meat is another man's poison.一个人的佳肴常为另一人的毒药.

One may sooner fall than rise.跌倒容易爬起难.

One may think that dares not speak.人可思其不敢言者.

One misfortune comes on the neck of another.祸不单行.

One must draw the line somewhere.人之所为，总有限度.

One must drink as one brews¹.自作自受.

One must howl with the wolves.入乡随俗.

One never loses anything by politeness.有礼貌对自己不会吃亏.

One never loses by doing a good turn.行善者决无一失.

one of these years猴年马月

One penny witgh right is better than a thousand without right.合法得来一个钱，胜过非法钱一千.

One ploughs, another sow; who will reap no one knows.有的耕，有的播，谁来收获很难说.

One rotten apple spoils the whole barrel.一只烂苹果烂一萝苹果.

One should eat to live, not live to eat.人为生而食，非为食而生.

One sin opens the door for another.一个罪恶常为另一个罪恶开门.

One sows another reaps.不劳而获.

One swallow does not make a summer.一燕不成夏.

One thorn of experience is worth a whole wilderness² of warning.一次痛苦的经验抵得上千百次的告诫.

One today is worth two tomorrow.把握住今天胜过两个明天。

One today is worth two tomorrows.今天一天抵明天两天.

One who can do everything can do nothing.什麽都能做，什麽都不行.

One woe³ doth tread upon another's heels.祸不单行.

One wrong (or false) move can lose the whole game.棋错一著，全盘皆输.

One wrong thought may cause a lifelong regret.一念之错可铸终生之恨.

One’s sin will find one out.坏事终归要败露。