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Unit 01
Relative Clauses
defining, non-defining & reduced
What is a Relative Clause?
A relative clause joins two ideas into one sentence by giving extra information about a noun. They are introduced by relative pronouns: who, whom, whose, which, that, where, when, why.
The woman who lives next door is a doctor. / Paris, which I visited last year, was amazing.
Relative Pronouns & Their Uses
| Pronoun | Refers to | Function | Example |
|---|---|---|---|
| who | people | subject / object | The man who called is my boss. |
| whom | people | object (formal) | The person whom you met is my teacher. |
| whose | people / things | possession | The boy whose bike broke is sad. |
| which | things / animals | subject / object | The book which I read was great. |
| that | people / things | subject / object (defining only) | The car that he drives is fast. |
| where | place | adverbial | The cafe where we met is closed. |
| when | time | adverbial | The year when we met was special. |
| why | reason | adverbial | The reason why I left was personal. |
Defining Relative Clauses
Used to identify exactly which person or thing we mean. They are essential to the meaning — without them, the sentence is incomplete. No commas are used.
- The student who studies hard will pass.
- The house where I grew up is beautiful.
- "That" can replace "who" or "which" in defining clauses.
- The pronoun can be omitted if it is the object: The book (that) I read was excellent.
Non-Defining Relative Clauses
Used to give extra, non-essential information. They are separated by commas and use who / which / whose — never "that".
- My sister, who lives in London, is a designer.
- The Nile, which is the longest river, flows through Egypt.
- Mr Brown, whose son is in my class, is a lawyer.
- The clause can be removed without changing the core meaning.
Reduced Relative Clauses
When the noun is the subject of the relative clause, we can reduce it to a participial phrase.
| Type | Full clause | Reduced |
|---|---|---|
| Active (-ing) | The man who is talking | The man talking |
| Active (-ing) | Students who study hard | Students studying hard |
| Passive (V3) | The car that was repaired | The car repaired |
| Passive (V3) | The books that were written by her | The books written by her |
Punctuation & Omission Rules
- ✅ Omit (object): The movie (that) I saw was amazing.
- ❌ Cannot omit (subject): The man who called is my friend.
| Rule | Defining | Non-Defining |
|---|---|---|
| Commas? | No commas | Commas required |
| "that" allowed? | Yes | Never |
| Omit pronoun? | Yes, if object | No |
C1 Patterns: Infinitive Relatives, Whereby & Of Which
| Pattern | Example | Note |
|---|---|---|
| the first / last / only + to-infinitive | She was the first woman to win the prize. | = the first woman who won |
| noun + to-infinitive (purpose) | We need a place to stay. · someone to talk to | = a place where we can stay |
| preposition + which + to-infinitive (formal) | He had nothing with which to write. | very formal |
| whereby (= by which) | a system whereby students can borrow laptops | formal / academic |
| the ... of which / whose (things) | a house the roof of which / whose roof was damaged | "of which" is more formal |
| reduced non-defining clause | The report, published yesterday, caused a scandal. | commas stay |
| , at which point / , in which case | The fire alarm rang, at which point everyone left. | sentential relative |
Annotated Examples
Subject
Verb
Auxiliary
Object
Adjective
Adverb
Preposition
Hover over any word to see its role.
subjectThe womanverbwho lives next doorverbis a doctor.
↳ Defining clause — essential, no commas.
subjectParis,which I visited last year,verbwas amazing.
↳ Non-defining clause — extra info, commas, "which" not "that".
subjectThe booksverbwritten by herverbare bestsellers.
↳ Reduced passive clause: that were written → written.
Common Mistakes
My sister, that lives in Paris, is happy.
→
My sister, who lives in Paris, is happy.
"That" is never used in non-defining clauses (with commas).
The man which lives there is rich.
→
The man who lives there is rich.
Use "who" for people, not "which".
The book which written by her is great.
→
The book written by her is great.
Reduced passive clause → past participle alone.
I met a man he is a pilot.
→
I met a man who is a pilot.
Must join with a relative pronoun: who.
That's the reason because I left.
→
That's the reason why I left.
Use "why" (not "because") after "the reason".
She was the first person who arriving.
→
She was the first person to arrive.
the first + to-infinitive.