THAT + WE = RELATIVE PRONOUN + PRONOUN
|1) This was the hotel that we stayed in for two weeks.
|2) She showed me the emeralds which she had brought back from South Africa.
|3) The smartphone that costs £200 is very good.
|4) Mrs. Smith, who is very smart, lives on the fourth floor.
|5) This is the car that John bought at an auction.
|6) My colleague with whom I'm doing the project should be here as soon as possible.
|7) That's the woman whose house has been broken into.
|8) A doctor is a person who looks after people's health.
|9) My new motorbike, which I paid a few thousand euros for, is not running well.
|10) Where is the letter that arrived this morning?
|THE RELATIVE PRONOUN CAN BE OMITTED:
RULE#1 only in defining relative clauses (without commas).
RULE#2 If the relative pronoun is followed by a noun or pronoun!
The book (which) I read last week was fantastic.
WHICH + I = RELATIVE PRONOUN + PRONOUN
The woman (who) the police arrested was found guilty of first-degree murder.
WHO + THE POLICE = RELATIVE PRONOUN + NOUN
|THE RELATIVE PRONOUN CANNOT BE OMITTED:
RULE#1 in non-defining relative clauses (with commas).
Gina, whom I met in the shop, invited me for a cup of tea. CORRECT
RULE#2 in defining relative clauses if the relative pronoun is followed by a verb!
I'm reading the Hunger Games which was written by Suzanne Collins.
WHICH + WAS WRITTEN = RELATIVE PRONOUN + VERB
RULE#3 after preposition + whom/which (at which, with whom, among whom etc.)
This is the house in which she was murdered. (FORMAL) IN WHICH cannot be omitted!