behind the scenes 后台；幕后的

wet behind the ears 有点幼稚无知

lie behind 曾经发生；是什么样的原因

Is it permitted to go behind the scenes?

我可以到后台去吗？

At that time she was still wet behind ears.

那个时候她还乳臭未干。

My friend throw his weight behind Hillary.

我朋友支持希拉里。

Some difficulties lie behind us, but greater ones lie ahead.

已经历了一些困难，但更大的困难还在前面。