B1–B2 grammar lesson

Relative Clauses

Relative clauses join ideas without repetition. The key question is whether the information identifies the noun or simply adds an extra detail.

About 20 minutes · Guided practice · 10-question mastery test

By the end of this lesson, you can…

UnderstandChoose who, which, that, whose and where.
ChooseDistinguish defining from non-defining information.
UseUse commas and omit object pronouns where appropriate.

The essential rules

Defining clauses

Essential information identifies which person or thing we mean. Do not use commas. That may replace who/which.

The student who emailed me needs help.

Non-defining clauses

Extra information does not identify the noun. Put it between commas. Do not use that.

Lina, who lives in Bogotá, teaches online.

Omitting the pronoun

In a defining clause, omit the relative pronoun only when it is the object—not when it is the subject.

The book (that) I ordered arrived. · The book that won is excellent.

See the pattern

Reference Pronoun Example
People who / that The colleague who called…
Things which / that The app which crashed…
Possession whose The writer whose book won…
Place where The café where we met…
Teacher tip: Remove the relative clause mentally. If the listener can still identify the noun, the clause is probably extra and needs commas.

Three mistakes to avoid

✕ My laptop, that is new, is slow.
✓ My laptop, which is new, is slow.

Do not use that in a non-defining clause.

✕ The woman which called…
✓ The woman who called…

Use who for people.

✕ The man lives next door is a doctor.
✓ The man who lives next door is a doctor.

A subject relative pronoun cannot be omitted.

Guided practice

Try each item before opening the answer.

1. Join: I met a designer. She works for a game studio.

I met a designer who works for a game studio.

2. Add punctuation: My uncle who lives in Lima is visiting. (I have one uncle.)

My uncle, who lives in Lima, is visiting. The detail is extra.

3. Can we omit the pronoun? “The film that we watched was moving.”

Yes: The film we watched… “That” is the object of watched.

4. Complete: That is the office ___ I had my first interview.

where — it refers to a place.

Final check

Mastery test

Target: 8/10

1. The woman ___ teaches us is from Canada.

Why: Who refers to a person and is the subject of the clause.

2. This is the camera ___ I bought online.

Why: That can refer to a thing in a defining clause.

3. Mr Patel, ___ daughter is an architect, is retiring.

Why: Whose expresses possession.

4. Which sentence is correctly punctuated?

Why: The clause adds non-essential information, so use commas and which.

5. The restaurant ___ we celebrated has closed.

Why: Where refers to the place of the celebration.

6. In which sentence can the pronoun be omitted?

Why: That is the object of sent; the other pronouns are subjects.

7. My phone, ___ is five years old, still works well.

Why: Use which in a non-defining clause.

8. The employee ___ desk is by the window can help.

Why: Whose shows that the desk belongs to the employee.

9. Choose the defining clause.

Why: The clause identifies which files are confidential.

10. Which is correct?

Why: Who refers to a person and acts as the clause subject.