在……前面： in front of…；in advance of；in the face of

在……的前面： at the head of；in front of …,

面對，在……前面： in front of

在……後面： in back of；,behind；at the back of

at the back of（=behind）；

太陽在雲層後面消失了。

The sun disappeared behind the cloud.

您是排在這位先生後面的。請在他後面等候。

You are next to this gentleman. Please wait behind him.

我知道那個人。他總是跟在漂亮女孩的後面。

I know that man. He is always after pretty girls.