1.Once bitten， twice shy.一朝被蛇咬，十年怕井绳。

2.One boy is a boy， two boys half a boy， three boys no boy.一个和尚挑水喝，两个和尚抬水喝，三个和尚没水喝。Observation is the best teacher.观察是最好的老师。

3.Offense is the best defense.进攻是最好的防御。

4.Old friends and old wines are best.陈酒味醇，老友情深。

5.Old sin makes new shame.一失足成千古恨。

6.Once a man and twice a child.一次老，两次小。

7.Once a thief， always a thief.偷盗一次，做贼一世。

8.The water that bears the boat is the same that swallows it up.水能载舟，亦能覆舟。

9.Observation is the best teacher.观察是最好的老师。

10.Wet behind the ears.乳臭未干。

11.One cannot put back the clock.时钟不能倒转。

12.One eyewitness is better than ten hearsays.百闻不如一见。

13.One false move may lose the game.一着不慎，满盘皆输。

14.One good turn deserves another.行善积德。

15.One hour today is worth two tomorrow.争分夺秒效率高。

16.One man‘s fault is other man’s lesson.前车之鉴。

17.Time and tide wait for no man.岁月无情;岁月易逝;岁月不待人。

18.Time tries all.时间检验一切。

19.Time tries truth.时间检验真理。

20.Time past cannot be called back again.光阴一去不复返。