defining relative clauses

use

to add essential information to a phrase

who / whom / that

people

• she is the girl who / that lent me £10 yesterday. → subject
• the girl (whom / that) you met at the party is tom's girlfriend. → object
• the person (who / whom / that) i was talking about is coming. → object

which / that

things

• that is the museum which / that is in front of the millennium bridge. → subject
• the book (which / that) i borrowed from you is on the table. → subject
• this is the smartphone (which / that) i've bought. → object

whose

possession

• that's the boy whose horse won an important race.
• the man (whose) car broke down is waiting for a tow truck.

where

places

• there are places where you always feel at home.
• this is the city where i grew up.

who / whom / that - which / that

• if the relative pronoun is followed by a verb, it is a subject pronoun. you cannot omit it. - example: the actor who won the oscar was very famous.
• you can omit object pronouns. - example: the people (who / that / whom) i met this morning are very friendly.
• in informal speech, when the verb in the relative clause needs a preposition, we can omit the relative pronoun, and we put the preposition at the end of the relative clause. - example: the restaurant i was talking about is the one we went to last night.