These exercises test the main types of relative clause patterns.

1. Defining and non-defining clauses

eg: The church which had been deserted for many years was demolished last year. (= defining clause - the relative pronoun refers to the subject of the main clause)

The relative pronoun "which" is used to refer to things, and can refer also to the whole of a previous clause.

eg: He managed to survive in the desert for three weeks without food, which was amazing. (= non-defining clause)

*** A defining clause is a clause which explains which person or thing you are talking about. For example, if you say "I met the woman who lives next door",  "who lives next door" is a defining relative clause.

*** A non-defining clause is a clause which does not identify or classify; it simply tells us more about a person or thing that has already been identified. An example of a non-defining clause is "Many colleagues like Jane, who came here last month".  In this sentence, "who came here last month" is a non-defining relative clause  because it gives further information about Jane, but it is not essential and can be omitted. 

a. "who" is used to refer to persons by stating what the person(s) does / do.

eg: The man who robbed you was arrested by the police yesterday.

b. "whom" is used to refer to persons through another action done by a different subject.

eg: The student whom the teacher had praised finally won the competition.

c. "whose" is used to refer to persons through their possessions.

eg: The family whose house is located on top of the hill is very wealthy.

Preposition + Relative Pronouns

Prepositions can come before relative pronouns.

• He was greatly liked by the people with whom he worked.
• London is the city in which I was born.
• We should finish this process quickly, after which we can proceed to another stage.
• There were a lot of people at the party, none of whom I knew.

The relative pronoun "that" can be used instead of "which", "whom" and "who" when the clause is defining, as in the following:

Ö : The man who / that is wearing a blue T-shirt is John.
Ö : The girl whom / that you saw yesterday is my sister.
Ö : That building which / that has forty storeys is very grand.

However, "that" cannot be used to replace "whose", or "which" when it is used in a non-defining relative clause.

Ö : That man whose face is scarred is behaving strangely.
Ö : That building, which has forty storeys, is up for sale.