example sentences
S=subject, O=object, P=possessive

notes

defining relative clauses

S

- The person who phoned me last night is my teacher.
- The person that phoned me last night is my teacher.

That is preferable

- The car which hit me was yellow.
- The car that hit me was yellow.

That is preferable

O

- The person whom I phoned last night is my teacher.
- The people who I phoned last night are my teachers.
- The person that I phoned last night is my teacher.
- The person I phoned last night is my teacher.

Whom is correct but formal. The relative pronoun is optional.

- The car which I drive is old.
- The car that I drive is old.
- The car I drive is old.

That is preferable to which. The relative pronoun is optional.

P

- The student whose phone just rang should stand up.
- Students whose parents are wealthy pay extra.


- The police are looking for the car whose driver was masked.
- The police are looking for the car of which the driver was masked.

Whose can be used with things. Of which is also possible.

non-defining relative clauses

S

- Mrs Pratt, who is very kind, is my teacher.


- The car, which was a taxi, exploded.
- The cars, which were taxis, exploded.


O

- Mrs Pratt, whom I like very much, is my teacher.
- Mrs Pratt, who I like very much, is my teacher.

Whom is correct but formal. Who is common in spoken English and informal written English.

- The car, which I was driving at the time, suddenly caught fire.




P

- My brother, whose phone you just heard, is a doctor.


- The car, whose driver jumped out just before the accident, was completely destroyed.
- The car, the driver of which jumped out just before the accident, was completely destroyed.

Whose can be used with things. Of which is also possible.

*Not all grammar sources count "that" as a relative pronoun.
**Some people claim that we cannot use "that" for people but must use "who/whom". There is no good
reason for such a claim; there is a long history of "that" for people in defining relative clauses
from Chaucer, Shakespeare and the Authorized Version of The Bible to Fowler's and Churchill.



















Taken from: https://www.englishclub.com/grammar/pronouns-relative.htm