Relative clauses. Extra information. Part 2
1. Prepositions + whom/which.

You can use a preposition before whom (for people) and which (for things).

For example, to whom, about whom, with whom, without which

Mr Brown, to whom I spoke at the meeting, is very interested in our proposal.

2. In informal English we can keep the preposition after the verb in the relative clause.

This is my friend form Canada, who I was telling you about.
Yesterday they visited the City Museum, which they had never been to before.
3. All of/ most of + whom/which

Mary has three sisters. All of them are married.

Mary has three sisters, all of whom are married.
In the same way you may use:

None of/neither of/any of/either of             
Some of/many of/much of/a few of             + whom (people)
Both of/half of/each of/one of/two of         + which (things)
Sue has a lot of friends, many of whom she was at school with.

Mike tried on two skirts, none of which fitted him.
You may also say the cause of which/ the name of which.

The building was destroyed in a fire, the cause of which was never established.
4. Which (not what)
Jim got the job. This surprised everybody.

Jim got the job, which surprised everybody.

Which = the fact that he got the job. You must use which in sentences:

Sam couldn’t meet us, which was a pity.

The weather was good, which we hadn’t expected.