Relative Clauses
Relative clauses give you information about something or someone. We start relative clauses with which if we are referring to a thing or an idea, and with who if we are referring to a person.
A diary is a book which you write in every day.
He’s the person who lives next door.
In these examples, both which and who can be replaced by that.
We can also form relative clauses with where and when. We start clauses with when if we are referring to a time, and with where if we are referring to a place.
July is a month when many people go on vacation.
A registry office is a place where a couple can get married.
We use whose in place of his, her or their in relative clauses.
The best man is the person whose job it is to help the groom.
They are the people whose car was stolen.
If who, which, or that is the subject of the relative clause, it must remain in the sentence. If it is the object, it can be omitted. Whose is always followed by a noun and cannot be omitted from its clause.
She’s the friend who likes to go to the theater with me.
She’s the friend (who) I like to go to the theater with.