B2 · Upper Intermediate

Relative Clauses

Add information, define nouns and connect ideas with precision — master who, which, where and whose in both defining and non-defining clauses.

Level: B2 Defining vs. non-defining Play · Practise · Score

The Grammar Transformer

Choose a pronoun. A clause type. A tense.

Four pronouns, two clause types, two tenses — 16 real sentences. See how the pronoun changes with the antecedent and how commas signal defining versus non-defining meaning.

The woman who sits next to me speaks four languages.

Structure:antecedent + who + verb phrase (no commas)

Who refers to a person in a defining clause — it restricts the meaning to identify exactly which person. You can replace who with that in informal English.

Got the pattern? Jump to the practice →

The rules — with examples

Defining versus non-defining clauses, the four key pronouns, and what you can and cannot swap.

Defining vs. non-defining clauses

Defining (restrictive)

No commas — the clause identifies which person or thing

The woman who called you is my manager.
The book that changed my life was a gift.

Non-defining (non-restrictive)

Commas required — the clause adds extra information

My manager, who called you, is very helpful.
This book, which won the Booker Prize, is excellent.

The comma test: remove the relative clause. If the sentence still identifies the right person or thing, it is non-defining → use commas. If the meaning becomes unclear or too general, it is defining → no commas. Never use that in a non-defining clause.

The four relative pronouns

who

Person — subject or object

The teacher who taught me still works there.
The colleague who(m) I admire got promoted.

Informal: that replaces who in defining clauses. Formal: whom when the pronoun is the object of the clause.

which

Thing or idea

The film which won the award was brilliant.
She passed, which surprised everyone.

In defining clauses, that or zero pronoun often replaces which. In non-defining clauses, only which is correct.

where

Place (or situation)

The city where I grew up has changed.
Prague, where she studied, is beautiful.

Formal alternative: in which / at which. Do not use which alone to refer to a place.

whose

Possession — people or things

The student whose essay won is in Class B.
A company, whose profits doubled, was sold.

Cannot be replaced by that. No article after whose: whose car, not whose the car.

Meaning changes with commas

Defining — identifies which one

The students who passed will get a certificate.

Only the students who passed get a certificate — others do not. The clause is essential.

Non-defining — adds extra information

The students, who all passed, will get a certificate.

All the students get a certificate. The fact they all passed is extra information.

Reduced relative clauses: when the relative pronoun is the subject, you can sometimes shorten it. The man who is standing by the door → The man standing by the door (active). The report which was written last week → The report written last week (passive). This only works in defining clauses.

What you can and cannot use

Defining clauses: who / that / which / that / where / whose — and you can often omit the pronoun when it is the object.

Non-defining clauses: who / which / where / whose only — never that, never zero pronoun.

whom = formal object pronoun for people: the person whom I spoke to. In informal English, who or zero pronoun is preferred.

Practise & score yourself

Ten questions — five multiple choice, five gap-fill. Instant scoring and a short explanation for every answer.

Your score

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Answer a question to begin.

The one rule to remember

Ask two questions: What is it? (person = who, thing = which, place = where, possession = whose) and Is this information essential? If yes — no commas, defining clause. If it’s extra information — commas required, non-defining clause, and never use that.

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