of表示从属关系？

Question

The MBA course normally attracts 30 students per year ____ whom up to half will

be from abroad.

A in
B of
C from

看了下答案说of是表从属关系，是说 一半学生 是 属于30 个学生中的就叫从属关系么？
from就没这个意思么？ 可是我常看到from表示来自那里那里啊。比如这样行不？
There are 30 students from abroad。

我就是不太明白这个从属部分，能否给点例句，让我区分一下from和of区别，谢谢！

Answer 1

of 表从属关系
介词Of的用法
（1）所有关系
This is a picture of a classroom
（2）部分关系
a piece of paper
a cup of tea
a glass of water
a bottle of milk
What kind of football,American of Soccer?
（3）描写关系
a man of thirty 三十岁的人
a man of Shanghai 上海人
（4）承受动作
The exploitation of man by man．人对人的剥削.
（5）同位关系
It was a cold spring morning in the city of London in England．
（6）关于,对于
What do you think of Chinese food?
你觉得中国食品怎么样?

Answer 2

up to half of the students will be from abroad.

那个是定语从句，把先行词放进去句子就清楚了。
there are 30 students from abroad。这个句子是对的本回答被提问者采纳