這些前置詞（短語）均含有“在……前”之意。
before（之前） : 指空間位置或時間的“在……前”。表時間時，反義詞為after；指空間位置時，其反義詞是behind。
You should always wash your hands before meals.
飯前應該洗手。
Before leaving he said goodbye to each of them.
走前他和每個人都告了別。
She's always up before dawn.
她總是黎明前就起床了。
Before he could reach the door, she quickly closed it.
他還沒走到門前她就迅速關上了門。
Before we make a decision, does anyone want to say anything else?
趁我們還未作決定，還有人想說什么嗎？
She had to give the doorman a tip before he would help her with her suitcases (= he would not do it until she had given him a tip).
她得給看門人小費，好讓他幫她提箱子。
in front of（前面） : 指在某地方之外的前面，即不在其中，多與靜態動詞連用，通常可與before通用。
She started talking to the man in front of her.
她開始跟前面的那個男人攀談起來。
I stood for a few moments in front of the nearest shop window.
我在最近的一家商店的櫥窗前站了一會兒。
They put a screen in front of me so I couldn't see what was going on.
他們在我面前豎了一面屏風，所以我看不到發生了什么事情。
We dried our clothes in front of the fire.
我們在火前烘干了衣服。
in the front of（前部） : 指在某地方之內的前面，即在其中的前部分。
The driver sits at the front of the bus.
駕駛員坐在公共汽車的前端。
Put the shortest flowers in the front (of the bunch).
把最短的花放在花束的靠前位置。
There is a table of contents in the front of a dictionary.
詞典的開頭有目錄表。
