In relative clauses whose is used instead of his, her, their. It can refer to people or things and whose + noun can be the subject or object of a verb or the object of a preposition.
Examples:
The other evening we met a young couple – their son was at school with ours.
The other evening we met a young couple whose son was at school with ours.
I’ll speak to the man – I took his wife to the hospital in the ambulance.
I’ll speak to the man whose wife I took to hospital in the ambulance.
I introduced the Director, with whose help, we had won the case.
The use of whose is usually considered fairly formal and other structures are sometimes preferred.
Examples:
Do you know the old lady whose son lives in the house next door?
Do you know the old lady with the son who lives in the house next door?
Do you see that chap over there whose hair is green and purple?
Do you see that chap over there with the green and purple hair?
Whom
Whom is often used instead of who when it is the object of the verb in the relative clause.
Examples:
The person whom I wanted to see, was in a meeting.
I have a number of people working for me, most of whom trained in New York.
Whom is sometimes used with a preposition to, with, from etc.
Examples:
The tour operator with whom I had booked, said he wasn’t responsible.
The assistant to whom I gave the parcel seemed to know where to take it
Where
Where can be used in a relative clause to talk about places.
Examples:
The clinic where I went wasn’t very good
It’s healthy to live in an environment where there is little pollution.
That is used in a relative clause if one is talking aboutthe day, the year, the time.
Examples:
Do you remember the day that we went to the Science Museum.
The first time that I saw her, she was wearing a hospital gown.