Two heads are better than one. 三个臭皮匠，顶个诸葛亮。

There are no two ways about it. 别无选择；毫无疑问的

be of two minds 三心二意

in two shakes of a lamb’s tail (as quickly as possible) 马上；很快

kill two birds with one stone 一石二鸟；一箭双雕

Two wrongs don’t make a right. “错错不得对” 不能利用别人的错误来掩饰自己的错误

Two’s company, three’s a crowd. 两人成伴，三人不欢。

give three cheers for (为...)欢呼三声(Hip, hip, hurrah!); (为...)三呼万岁

six of one, half a dozen the other 半斤八两

in seventh heaven 暗喻心情极为快乐、满足

on cloud nine 高兴得飘飘然

dress to the nines 穿着非常时髦华丽

a hundred to one shot 百分之一的可能；表示可能性很小

forty winks 打盹

at the eleventh hour 最后一刻 

与数字有关的实用短语|英语学习