三思而后行
Think twice before you do.
字面意思：你做之前（把事情）想两遍。三思就是多思考一下，思考两遍 think twice。
运用：做任何事前都要三思而后行。Think twice before you do everything.
半斤八两
Six of one and half a dozen of the other.
字面意思：一个是六，另一个是一打（十二个）的一半。不相上下
运用：他们两个的实力半斤八两。Their abilities are six of one and half a dozen of the other.
一模一样
Two peas in a pod.
字面意思：一个豆荚里面的两个豆，（长得一模一样）。a pod 豆荚
运用：这两个人一模一样。They two are two peas in a pod.
一箭双雕
Kill two birds with one stone.
字面意思：用一个石头杀两只鸟。一箭就是一支箭 one arrow, 也可以说一个石头 one stone。双雕是两只鸟 two birds。
运用：你这个方法很好，一箭双雕。Your method is really great. Kill two birds with one stone.
十有八九
Nine times out of ten.
字面意思：十次里面就有九次。意思就是很有可能。
运用：这十有八九是假的。It is false nine times out of ten.
一个巴掌拍不响
It takes two to tango.
字面意思：跳探戈舞（双人舞）需要两个人。tango 探戈舞是个双人舞，在这里是动词，跳探戈舞。takes 花费，需要。
运用：他们两个打架，一个巴掌拍不响（不能只责怪某一个）。They two fight with each other, but it takes two to tango.