例句：But with any luck, we could solve the problem in two shakes of a lamb's tail.
6.kill two birds with one stone 一箭双雕，一举两得
例句：I always get my nails manicured while I get my hair cut, that way I can kill two birds with one stone.
7.two wrongs don't make a right 负负不得正
例句：But we must remember that two wrongs don't make a right. If someone does something bad to you, you should not do the same to him.
8.two's company, three's a crowd 俩人结伴，三人添乱
例句：Two's company, three's a crowd, so please don't come with my girlfriend and me.