Who, which or that? Twelve relative-clause exercises with answers

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You want to describe “the friend who helps me” or “the book you recommended”. English relative clauses let you connect these ideas without repeating the same noun. Choosing who, which or that is only part of the task: meaning, commas and the pronoun’s job all matter.

This twelve-question workshop uses three checks: What does the clause refer to? Does it identify someone or something, or add extra information? Is the pronoun the subject or the object? Try the exercises without help first. Then use the explanations and answer keys to identify what went wrong, rather than simply counting correct answers.

People, things and the place of that

A relative clause usually follows the noun or noun phrase it describes:

• I have a friend who helps me.
• This is a book which inspires me.
• This is a book that inspires me.

The last two sentences show that more than one form can be correct.

That can refer to people too: a friend that helps me is possible. Who is a useful starting choice for people. Who is also sometimes used for pets; the table gives the usual basic distinction. Cambridge’s guide to relative pronouns explains these uses. Which is grammatical in defining clauses, although some editorial styles prefer that there.

Decide what you mean before adding commas

A defining relative clause identifies the person or thing you mean:

The students who finished early went home.

This selects the students who finished early. It does not say that every student did. There are no commas around the clause.

A non-defining relative clause adds information about someone or something already identified:

The students, who finished early, went home.

Here, the students being discussed all finished early and went home. The clause adds information about the whole group. If the extra clause is in the middle, put a comma on each side; if it ends the sentence, put one before it.

In a non-defining clause, use who or which, not that:

• Maya, who lives nearby, is coming tonight.
• My bike, which is ten years old, still works well.

The commas signal a difference in meaning. They are not simply optional pauses. The ego4u overview also contrasts the two clause types, with explanations in German.

When can you leave out the relative pronoun?

In a defining clause, you can often omit an object pronoun. You cannot omit a subject pronoun. To find its role, turn the relative clause back into a simple statement.

The pronoun is the subject: keep it

The woman who called me is our neighbour.

The simple statement is The woman called me. The woman does the calling, so who is the subject of called. You need who or that. The woman called me is our neighbour does not work as this relative-clause construction.

Another person is the subject: omission is possible

The woman who I called is our neighbour.

The simple statement is I called the woman. I is the subject; the woman is the object. You can also say:

• The woman that I called is our neighbour.
• The woman I called is our neighbour.

The same test works for things: the book which I bought → the book I bought. Keep the pronoun in a non-defining clause even when it is the object: Maya, who I called yesterday, is coming tonight.

Three common mistakes to catch

1. Do not repeat the subject or object. Say the woman who lives here, not the woman who she lives here. Say the book that I bought, not the book that I bought it.
2. Do not replace the pronoun with what after a noun. Use the book which/that I bought, not the book what I bought. What I bought, without a preceding noun, is a different pattern.
3. Check prepositions. The person who I spoke to and the person I spoke to are everyday options. The person to whom I spoke is more formal. Do not put that immediately after a fronted preposition in this pattern.

For possession or relationships, use whose + noun: a friend whose sister lives in London. Whose is different from who’s, which means who is or who has.

Six exercises: choose a form and explain why

Fill each gap with all suitable options from who, which and that. Decide whether leaving it empty is possible too. For question 6, combine the statements.

1. I need a colleague ___ speaks French.
2. The laptop ___ I bought last week is already broken.
3. My uncle Leo, ___ lives in Bristol, is visiting us.
4. The café, ___ opened last month, is very busy.
5. The people ___ we invited are here.
6. I found the keys. You lost the keys. Start with I found the keys …

Answers and explanations

1. who / that. A person in a defining clause; the pronoun is the subject of speaks, so keep it.
2. which / that / no pronoun. A thing in a defining clause; I is the subject and the laptop is the object of bought.
3. who. A non-defining clause with commas: no that and no omission.
4. which. Extra information about a thing: no that and no omission.
5. who / that / no pronoun. People in a defining clause, with we as the subject of invited. Whom is also possible in a more formal style.
6. I found the keys which/that you lost, or I found the keys you lost. The keys are the object of lost. Do not add them again at the end.

Six transfer tasks: repair sentences and choose the meaning

7. Correct: The neighbour who she waters our plants is away.
8. Correct: The film that we watched it was funny.
9. Correct: My friend Ava, that works in a hospital, is here.
10. Join with whose: I know a musician. Her brother teaches piano.
11. Four of ten employees work at night. Only those four receive extra pay. Complete and punctuate: The employees ___ work at night receive extra pay.
12. Every employee in the team already being discussed works at night. Write the same sentence with that detail as extra information.

Transfer answers

7. The neighbour who waters our plants is away. Remove she because who already supplies the subject. That is also possible.
8. The film that we watched was funny. Remove it. Which or no relative pronoun is also possible here.
9. My friend Ava, who works in a hospital, is here. A non-defining clause needs who rather than that.
10. I know a musician whose brother teaches piano. Whose links the musician to her brother; do not add her.
11. The employees who/that work at night receive extra pay. No commas: the clause selects four employees out of ten.
12. The employees, who work at night, receive extra pay. Commas: the extra detail applies to the whole team already identified. No that.

Turn the rule into a short practice session

Write three pairs of statements about people and things in your life. Join each pair, underline the noun being described and decide whether the information identifies it or adds a detail. Then check the subject–object relationship. Cover your answer and say the whole sentence again.

For regular phrase study alongside this exercise, Lingo Phrase Cards offers prepared language sets. Choose an available language direction and an accessible set. Target-language phrases include IPA and audio. In regular study, answer before turning the card over; your assessment determines the Leitner review schedule. Free pool, box and mistake-card practice lets you go through cards again without changing card progress.

Do the twelve exercises above separately on paper. For related practice, explore learning vocabulary in context or see how the job of who changes in English questions with do, does and did.

Remember: choose by reference, decide the meaning and commas, then check whether omission is possible. Visit the Lingo product page to explore available language directions and sets.