observation is the best teacher.

1、观察是最好的老师。

offense is the best defense.

2、进攻是最好的防御。

old friends and old wines are best.

3、陈酒味醇，老友情深。

old sin makes new shame.

4、一失足成千古恨。

once a man and twice a child.

5、一次老，两次小。

once a thief, always a thief.

6、偷盗一次，做贼一世。

once bitten, twice shy.

7、一朝被蛇咬，十年怕井绳。

one boy is a boy, two boys half a boy, three boys no boy.

8、一个和尚挑水喝，两个和尚抬水喝，三个和尚没水喝。

one cannot put back the clock.

9、时钟不能倒转。

one eyewitness is better than ten hearsays.

10、百闻不如一见。

one false move may lose the game.