1. of表示同位关系：即用于在A+of+B结构，其中的A和B为同位关系。如：

Her sons, both of whom work abroad, ring her up every week. 她的两个儿子，都在国外工作，他们每周都给她打电话来。

We’ve tested three hundred types of boot, none of which is completely waterproof. 我们已经测试过300种靴子，没有一种是完全防水的。

2. of表示整体与部分的关系：即用于“部分+of+整体(which, whom)”结构。如：

He went with a group of people, few of whom were correctly equipped for such a climb. 他和一队人一起去了，其中没有几个人配有进行这样一次登山的适当装备。

The buses, most of which were already full, were surrounded by an angry crowd. 公共汽车大多数都已经挤满了人，它们被愤怒的人群包围着。

I met the fruit-pickers, several of whom were university students. 我遇到了摘水果的人们，其中有几个人是大学生。

3. of表示所属关系：即of用于构成所有格。如：

He’s written a book the name of which I’ve forgotten. 他写了一本书，书名我给忘了。

The house the roof of which was damaged has now been repaired. 那幢屋顶被损坏的房子现在已经修好了。

4. of与其他的词构成固定搭配：即of与从句中的某个词语构成固定搭配。如：

He’s married to a singer of whom you may have heard. 他与一位歌唱家结了婚，你可能听说过这个人。(介词of与动词hear构成固定搭配，意为“听说”)

注意：介词of后面除接关系代词which, whom外，有时也可能是whose。如：

She had a teddy-bear, both of whose eyes were missing. 她有一个玩具熊，它的两只眼睛都丢了