Kilo Lingo
English grammar Part of Chapter 13

CEFR B1-B2

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Test yourself (21 questions)

Relative clauses in English: defining and non-defining

By Michael McGettrickUpdated 12 October 2026

A relative clause tells you more about a noun. It starts with a word like who or which, and it joins two sentences into one:

.
the relative wordthe noun it tells you aboutWhat do the colours mean?
WordForExample
,

Quick check

Now use it: three quick questions on the chart above. The full practice is further down.

Pick the right one

0/3

Tap the word that fits.

  1. The doctor saw me was very kind.

  2. Is this the bus goes to the station?

  3. This is the town I was born.

Who, which and that: people and things

the relative wordthe noun it tells you aboutWhat do the colours mean?

Two sentences become one. She or it goes, and who or which takes its place:

She becomes who

is for people:

Four people in their work clothes: a woman doctor with long hair and a bow, in a white coat with a stethoscope; a man teacher with glasses, a moustache and a tie, pointing at a board and holding a book; a man cook with a moustache, in a chef's hat and apron, holding a frying pan with an egg; a man police officer with a moustache, in a blue uniform and cap.
  1. .
  2. .
  3. .
  4. .

A doctor helps ill people. A teacher teaches. A chef cooks food. A police officer keeps us safe.

is for things and animals. works for both:

Thing or personExample
: .
: .
: .
: .

With people, who is the usual choice; that is fine too. Never which for a person: the man which called is wrong. With pets, people often say who: our dog, who is twelve.

Whose, where and when

the relative wordthe noun it tells you aboutWhat do the colours mean?

tells you who something belongs to. It always comes before a noun:

  • . (her father is a doctor)
  • .

Whose is not who's (who is): the woman whose bag was stolen, not who's bag.

is for places, for times:

WordExample
born.
.
.

After day, year or time, you can leave out when:

.

Commas: which one, or extra news?

the relative wordthe noun it tells you aboutWhat do the colours mean?

Ask one question: does the clause tell you ?

KindCommas?Example
.
, 70, .

You have one mother, so who is 70 does not tell you which one. It is extra news: take it out, and My mother still works is complete.

The commas can change the meaning:

  • Leeds . (I have more than one sister: this one)
  • , Leeds, . (I have one sister; she lives in Leeds)

Leaving out who, which or that

the relative wordthe noun it tells you aboutWhat do the colours mean?

Look at the word after who, which or that. Is it a new subject (I, you, she, we)? Then you can leave the relative word out:

With the wordWithout

Is it a verb? Then the word must stay:

Noun
Word
Next word
The rest
()
.
.

The man called is my boss is wrong: who does the calling, so it stays. After a comma, the word always stays.

A clause can get shorter still: the man sitting by the door. That is on participle clauses.

Common mistakes

WrongRightWhy
the man who he livesthe man who lives .
the film I saw itthe film I saw .
my car, that is red,my car, which is red, comma.
the teacher which...the teacher who...: .
who's bagwhose bag: .
a car what I likea car that I like noun.

What means the thing that, and it cannot follow a noun in standard English. It has its own job: What I need is time. See cleft sentences.

What to do next

  1. Describe three people you know: my friend who...
  2. Describe your town: the place where...
  3. Do the drills below.

Practise: test yourself

Pick the right one

0/5

Tap the word that fits.

  1. The doctor saw me was very kind.

  2. Is this the bus goes to the station?

  3. This is the town I was born.

  4. I remember the day we met.

  5. That's the girl father is a doctor.

Sort into groups

0/6

Can you leave out the word in brackets?

Tap a word, then the group it belongs in.

Spot the mistake

0/4

Each sentence has one mistake. Tap it.

Put the words in order

0/2

Join the two sentences with who or which.

  1. I know a woman. She teaches French.

    Your sentence is empty.

  2. This is the phone. It broke.

    Your sentence is empty.

Complete the story

0/4

Tap the word that fits each gap.

My street

I live in a small street everybody knows everybody. My neighbour, is a doctor, has a big dog. The boy mother runs the shop gives it bread. And the cafe opened last week is always full.

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Frequently asked questions

When should I use who and when should I use that?
Who is for people, which is for things, and that works for both. The woman who called and the woman that called are both fine. But after a comma, use who or which, never that: My mother, who lives in Leeds, is a nurse.
How do I know when to put commas around a relative clause?
Ask: does the clause tell you which one? If yes, no commas: The man who fixed my car is here. If it only adds extra news about someone you already know, use commas: My brother, who lives in Leeds, is a nurse.
When can I leave out who, which or that?
When a new subject comes straight after it: the book (that) I read, the woman (who) I met. You cannot leave it out when a verb comes next: the man who called needs its who.
What does whose mean?
Whose shows who something belongs to: the girl whose father is a doctor (her father is a doctor). Do not mix it up with who's, which is short for who is.
Can I use which for people?
No. Use who or that for people: the teacher who teaches maths, not the teacher which teaches maths. Which is for things and animals.