" Look before you leap" is a warning against people acting rashly.

“三思而后行”这条谚语是告诫人们不要鲁莽行事。

But you never look before you leap.

但你行动之前从不看路。

And sometimes, it's better to look before you leap.

有时，最好三思而后行。

You'd better look before you leap. I don't think you really understand the situation.

你最好三思而后行。我觉得你还没真的了解状况。

I think it is necessary to look before you leap.

我觉得三思而后行是有必要的。

Sometimes, " expression" is used to refer to what we would also call a " saying" – a traditional expression, such as " You should look before you leap."

有时，“expression”指的是我们也称为“saying” 的东西——一种传统的表达方式， 例如“You should look before you leap” 。