一、 in front of，表示在一物外部的前面，而不是在一空间内的前部，比如在房前。
We gave her the quilt in front of the house.
我们在房前把被子送给了她。
We are standing in front of the car.
我们站在汽车前面。
She is standing in front of the blackboard.
她站在黑板前面。
I stood for a few moments in front of the nearest shop window.
我在最近的一家商店的橱窗前站了一会儿。
They put a screen in front of me so I couldn't see what was going on.
他们在我面前竖了一面屏风，所以我看不到发生了什么事情。
He is in front of us.
他在我们前面。
二、in the front of，表示在一样内部空间的前部，比如司机在汽车前排开车，老师在教室内前面讲课。
The baby and I were in the front of the car.
宝宝和我在车子前排。
She is standing in the front of the classroom.
她站在教室前面。
There is a table of contents in the front of a dictionary.
词典的开头有目录表。
I'd like a seat in the front of the plane.
我想要靠飞机前段的的座位。
If your cramp is in the front of your thigh, then bend your knee.
如果你是大腿前侧抽筋，弯曲膝盖。