Of Which vs Of Whom
1. We can use a non-defining relative clause with “of which” and “of whom” after quantifiers:
All, both, each, many, most, neither, none, part, some…
For Example:
Adam has two brothers. Both of them work as an engineer.
Adam has two brothers, both of whom work as an engineer.
Brad has very nice neighbors. I like all of them very much.
Brad has very nice neighbors, all of whom I like very much.
My mother invited many relatives to my birthday. Only a few of them showed up.
My mother invited many relatives to my birthday, only a few of whom showed up.
I talked to an old friend of mine last night. Some of her remarks offended me.
I talked to an old friend of mine last night, some of whose remarks offended me.
2. After a number(one,two etc.; the first, the second etc.; half, a third etc.)
I want to be flatmate with my friend Daniel. One of his biggest interests is playing basketball.
1 want to be flatmate with my friend Daniel, one of whose biggest interests is playing basketball.
There are many books in our school library. I’m quite interested in two of them.
There are many books in our school library, two of which I’m quite interested in.
3. After superlatives (the best, the biggest etc.)
Yesterday, my friend and I caught a lot of fish. The biggest of them was 20 pounds.
Yesterday, my friend and I caught a lot of fish, the biggest of which was 20 pounds.
I met with many beautiful girls at the party last night. The most beautiful of them was Nora.
I met with many beautiful girls at the party last night, the most beautiful of whom was Nora.
4. We can use “of which” instead of “whose” for the objects but “of which” is used in non-defining relative clauses.
This is the machine. I described its properties.
This is the machine whose properties I described.
This is the machine, the properties of which I described.
I stayed at a good hotel. It’s facilities are fabulous.
I stayed at a good hotel whose facilities are fabulous.
I stayed at a good hotel the facilities of which are fabulous.