Relative Clauses
Level B2 · Relative Clauses
A relative clause adds information about a noun without starting a new sentence, combining two related ideas into one: The woman is my neighbour. She lives next door becomes The woman who lives next door is my neighbour.
Choose the relative pronoun based on what it refers to:
- who/that for people, which/that for things, whose for possession, where for places, when for times: the man who called, the book that/which I read, the woman whose car broke down, the café where we met, the year when I was born.
- A defining relative clause identifies which exact person or thing is meant — no commas, and that is fine here: The book that I borrowed was great (without the clause, you wouldn't know which book).
- In a defining clause, the pronoun can be dropped if it's the object of the clause: The book (that) I borrowed was great — but not if it's the subject: The man who called (not The man called, meaning someone who called).
Non-defining clauses add extra, non-essential information, and behave differently from defining ones:
- Set off by commas, and that is never allowed: My brother, who lives in Spain, is a doctor (not My brother, that lives in Spain...) — removing the clause still leaves a complete, sensible sentence.
- The pronoun in a non-defining clause can never be dropped, even if it's the object: My car, which I bought last year, has already broken down (not My car, I bought last year, has already broken down).
- A relative clause can often be reduced by dropping the pronoun and be: active clauses reduce to -ing (the man who is standing there → the man standing there); passive clauses reduce to the past participle (the car which was stolen → the car stolen).
The most common mistake is using that in a non-defining (comma) clause: My brother, that lives in Spain, is a doctor is wrong — that never follows a comma; use who/which instead. A second frequent error: leaving who/which/that in a reduced clause instead of dropping it along with be: the man who standing there is wrong — reduce it fully to the man standing there.
Look for who/which/that/whose/where/when introducing extra information about a noun, commas signalling non-defining information (where that is impossible), and an -ing or past participle sitting right after a noun with no pronoun or be — a sign of a reduced relative clause.