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Relative Clauses: who / which / that

B1 Grammar

📖 16 min read + practice⚡ Intermediate difficulty❓ 50-question quiz included

B1 · Lesson 9 of 14 in this level

1. Simple explanation

A clause is a group of words with a subject and a verb — like a small, complete piece of a sentence. A relative clause is a clause that adds information about a noun (a noun is a word for a person, thing, or place). It starts with a relative pronoun — a small joining word — and comes right after that noun: 'The man who lives next door is kind.' The clause 'who lives next door' tells us more about 'the man.' The pronoun changes with the noun: who for people, which for things, and that for both.

2. Detailed explanation

Start from zero. A noun is a word for a person, a thing, or a place: man, book, city. A clause is a group of words with a subject and a verb — the subject is who or what the words are about. 'The man smiled' is a clause: the man (subject) smiled (verb). A relative clause is a clause that adds information about a noun. 'Relative' means 'connected' — it connects to the noun before it and describes it. Without one you need two sentences: 'I know a man. He speaks Arabic.' With one: 'I know a man who speaks Arabic.' The joining word — who, which, or that — is called a relative pronoun: a pronoun is a small word standing in for a noun; this one also joins the clause.

Choose the pronoun by the noun. People take who (that works too, informally). Things and animals take which or that. Take 'The woman who called you is my boss' apart, word by word: The woman (the noun we describe) + who (stands for her and joins the clause) + called you (what she did) + is my boss (the main sentence continues). The clause answers 'Which woman?' Now compare 'The phone that I bought is broken.' Here that is the object — the thing the action happens to — because I is the subject of bought. In the first sentence who is the subject of its clause — she did the calling. Subject or object decides the next rule.

When the pronoun is the object, you can drop it: 'The phone I bought is broken' is perfect, because 'I bought' already has a subject. When the pronoun is the subject, never drop it — without who, 'The woman called you is my boss' breaks. Also learn whose — it shows possession, belonging: 'The man whose car was stolen called the police' (his car). Where adds a place: 'the town where I grew up.' When adds a time: 'the day when we met.' Formal English also has whom, the object form for people — 'the man whom I saw.' It is correct, but Americans almost never say it; they use who, that, or nothing.

Sometimes the clause only adds a bonus fact about someone already identified: 'My brother, who lives in Cairo, is a teacher' — I have one brother, so no map is needed. Commas wrap this extra-information clause. With commas, never use that — choose who or which — and never drop the pronoun. In natural speech, small words like to and at move to the end: 'the man I talked to.' Putting them first ('the man to whom I talked') is formal writing.

Remember this first: three rules cover nearly everything. One: who is for people, which is for things, that is for both. Two: drop the pronoun only when it is the object — 'the book I read,' never a subject. Three: after a comma, use who or which, never that.

3. Formula / structure

Step by step — how to build a sentence:

1) Write two sentences with the same noun: 'I read a book. The book was exciting.' 2) Decide the pronoun: person → who, thing → which/that. 3) Replace the second noun with the pronoun and glue the second sentence right after the first noun: 'I read a book that was exciting.' 4) Check: is the pronoun the object of its clause ('the book that I read' — I did the reading)? Then you may drop it: 'the book I read.' Object example: 'She is the doctor. I visited her.' → 'She is the doctor (that) I visited.'

object relative (pronoun can drop):

noun + who/which/that (optional) + subject + verb → The song (that) she sang was beautiful. / The man (who) I met was kind.

subject relative (pronoun stays):

noun + who (people) / which / that (things) + verb → The girl who won is my niece. / The car that stopped was red.

where / when:

noun of place + where + subject + verb → the house where I was born. | noun of time + when + subject + verb → the year when I moved.

whose (possession):

noun + whose + noun + verb → The student whose phone rang apologized.

4. When to use it

Identifying which person or thing you mean: 'The woman who called is my sister.' (not the other women)
Describing instead of using two choppy sentences: 'I bought a car that uses little gas.'
Adding extra information with commas: 'My uncle, who is 90, still drives.'
Showing possession: 'The boy whose bike was stolen is crying.'
Talking about places and times: 'the city where I was born,' 'the moment when I saw her.'
Giving recommendations: 'I need an app that translates speech.'

5. When NOT to use it

Don't drop the pronoun when it is the subject of the clause: ✗ 'The woman lives upstairs called me' → ✓ 'The woman who lives upstairs called me.'
Don't use 'that' after a comma: ✗ 'Mr. Park, that teaches math, is ill' → ✓ 'Mr. Park, who teaches math, is ill.'
Don't repeat the noun or pronoun inside the clause: ✗ 'the house that I bought it' → ✓ 'the house that I bought.'
Don't use 'what' as a relative pronoun: ✗ 'the things what I need' → ✓ 'the things that I need.' ('What' means 'the thing that' only when it starts its own clause.)
Don't put a comma when the clause identifies which one: ✗ 'The bag, that is on the chair, is mine' (defining) → ✓ 'The bag that is on the chair is mine.'

6. Positive examples

The man who lives next door is a doctor.
She is wearing the dress that I gave her.
The students who passed the exam were happy.
This is the hotel where we stayed last summer.
I remember the day when we first met.
The woman whose dog won the show was delighted.
The laptop which he bought is very fast.
Do you know the people who moved in yesterday?
The restaurant that serves sushi is on this street.
He showed me the photos that he took in Japan.
The teacher who helped me most was Mrs. Reed.

7. Negative examples

The man who called you isn't home.
The store that we visited wasn't cheap.
I don't like people who are always late.
The food which they served wasn't fresh.
That is not the book that I ordered.

8. Questions

Is this the book that you were looking for?
Do you know the woman who is talking to Ben?
Where is the phone that I left on the desk?
Who is the man that just walked in?
Did you finish the report which I sent you?
Can you recommend a hotel that is near the airport?

9. Short answers

Which bag is yours? — The one that is on the chair.
Who is that woman? — She's the teacher who helped me.
Which hotel do you mean? — The one where we stayed in May.
Do you like the gift? — Yes, it's the book that I wanted.
Who called? — A man who works with your brother.

10. Common mistakes

✗ The man who he lives next door is a doctor✓ The man who lives next door is a doctor.Why: 'who' already does the job of 'he' — never use both a relative pronoun and a normal pronoun for the same person.

✗ The book who I read was great✓ The book that I read was great.Why: 'who' is only for people. Books and things take 'which' or 'that'.

✗ She is the teacher taught me English✓ She is the teacher who taught me English.Why: 'who' is the subject of 'taught' — a subject pronoun can never be dropped.

✗ My car, that is ten years old, still works✓ My car, which is ten years old, still works.Why: after a comma, English never uses 'that.' Use 'who' for people and 'which' for things.

✗ The woman who's car is red is my aunt✓ The woman whose car is red is my aunt.Why: 'who's' means 'who is.' Possession — belonging — needs 'whose.'

✗ This is the place which I was born✓ This is the place where I was born.Why: a place needs 'where' when the clause has its own complete action — 'I was born' is complete, so there is no object for 'which' to be.

✗ The students, who passed the test, celebrated yesterday in a defining list of only the passing students✓ The students who passed the test celebrated.Why: when the clause tells us WHICH students — only some of them — it is essential information, so no commas.

11. American English notes

🇺🇸 American English

Americans strongly prefer 'that' in defining clauses: 'the book that I read,' 'the people that live here.' 'Which' for things is correct, but heavy use of 'which' can sound British or formal in the US. In speech, Americans drop the object pronoun very often: 'The guy I met,' 'The song you sent me.' 'Whom' is almost never spoken in the US — you will hear it in formal writing, legal documents, and fixed phrases like 'To whom it may concern.' Prepositions go at the end in natural American speech: 'the person I was talking to,' 'the hotel we stayed at.' The textbook pattern 'the person to whom I was talking' is correct but sounds stiff.

12. Similar grammar — comparison

Compare

Compare relative clauses with simple joining words (and/but). 'And' joins two equal sentences: 'I met a man, and he was very kind.' A relative clause instead puts the extra information inside one sentence, right after the noun: 'I met a man who was very kind' — one smooth sentence, and the focus stays on the man. Also compare who / whose / whom, the three people-words that learners confuse: who does the action ('the girl who won'), whose shows possession ('the girl whose bag was stolen'), and whom receives the action in formal English ('the girl whom I saw'). Who and whom differ exactly like he and him: if you can answer with 'him,' formal English wants 'whom.'

13. Natural spoken English

'You know the guy I work with? He just quit.'
'That's the place we went to last year.'
'The girl that's dating my brother is really nice.'
'Everything you said was true.'
'Is this the one you wanted?'
'My neighbor, who's super friendly, has three cats.'

14. Real-life examples

At a store: 'I'm looking for the shoes that were on sale.'
Describing a friend: 'She's the one who works at the hospital.'
Online reviews: 'A great hotel which has a pool and free breakfast.'
Lost and found: 'The bag that I lost is black, with a silver zipper.'
At work: 'The manager who interviewed me was very friendly.'
Travel: 'We visited a village where my grandfather was born.'

15. Mini dialogue

AExcuse me, I lost my bag at the station.

BCan you describe it?

AIt's a blue bag that has a red stripe.

BThere is a man who found a blue bag this morning.

AIs it the one that was left on the train?

BMaybe. The guard who is sitting over there has it.

AThe woman whose office is near the door helped me earlier.

BLet's ask her — she knows everyone who works here.

16. Summary

A relative clause describes the noun before it: who for people, which for things, that for both. The pronoun can be dropped only when it is the object; after a comma, use who or which, never that.

17. Practice exercises

Warm up with the first questions, then take the full quiz — every answer has a detailed explanation (parts 19–20 of this lesson: answer key + explanations live inside the quiz feedback).

18. The full quiz

50 questions, mixed formats, in difficulty order: easy → medium → intermediate → challenging → advanced.

Take the 50-question quiz

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← Previous: Reported Speech: He Said (That)… Next: Used To: Past Habits & States → Related lessons: Conjunctions & Linking Words: and / but / because / so · Question Forms & Word Order in Questions Practice test: 50 questions

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