🗺️ RELATIVE CLAUSES GRAMMAR MAP

DEFINING RELATIVE CLAUSES (Essential Info - No Commas)

Provides essential information to identify the noun. Cannot be removed.

(+) Positive The man who lives next door is nice • The car that I bought is fast

(-) Negative no commas used!

(?) Question Do you know the boy who won the race?

NON-DEFINING RELATIVE CLAUSES (Extra Info - Surrounded by Commas)

Provides extra background information. Can be omitted without losing core meaning.

(+) Positive My father, who is 60, still works • London, which is big, is expensive

(-) Negative NEVER use "that" in non-defining clauses!

(?) Question Have you visited Paris, which is in France?

1. Form & Structure

Defining vs Non-Defining Clauses Comparison Matrix

Defining Clause (Essential): The doctor who treated me was kind. (Which doctor? The one who treated me). NO COMMAS!
Non-Defining Clause (Extra Info): Dr. Smith, who treated me, was kind. (We already know his name!). COMMAS REQUIRED!
Use of THAT: "That" can replace who/which ONLY in Defining clauses! Never use "that" after a comma.
Omission of Relative Pronoun: Can omit who/which/that ONLY in Defining clauses when it acts as an OBJECT.

Example / Question	Positive / Short Answer	Negative / Short Answer
Defining: Essential info	The house that I built is big.	No commas & Can use "that"
Non-Defining: Extra info	My house, which I built in 2010, is big.	COMMAS required & CANNOT use "that"
Pronoun Omission	The movie (that) I watched was good.	Omit "that" because "I" is subject

2. Key Rules & Formation

Rule	Base / Standard Form	Applied Form
No "That" After Commas Rule	NEVER use "that" in a non-defining relative clause (after a comma)! Use who or which instead.	My brother, who lives in Hanoi (CORRECT) vs My brother, that lives in Hanoi (WRONG)
Comma Rules for Extra Information	Use commas before and after non-defining clauses because they add non-essential extra detail.	Paris, which is beautiful, is expensive.
Object Pronoun Omission Rule	You can omit who/which/that ONLY in defining clauses when followed by Subject + Verb.	The car (which) I bought

3. Practical Usage & Examples

1. Identifying specific people or objects clearly

Distinguish one item out of many possibilities in defining clauses.

The student who sits at the front gets top marks.

2. Adding interesting background information seamlessly

Enrich your writing with details separated by commas.

My grandmother, who is 85 years old, still swims every day.

3. Connecting thoughts without repeating nouns

Build complex, fluent sentences.

I bought a camera, which broke after two days.

4. Signal Words & Usage Context

defining clausenon-defining clausecommaswhowhichthatwhose

Punctuation Check:

No Commas → Defining (That allowed)
Commas Present → Non-Defining (NO That!)

💡 Common Mistakes & Memory Tips

Mistake 1: Using "that" after a comma in non-defining clauses
❌ Incorrect: My mother, that is a doctor, works hard.
✓ Correct: My mother, who is a doctor, works hard.
Note: Never use "that" in non-defining clauses with commas.
Mistake 2: Putting commas around essential defining clauses
❌ Incorrect: The car, that was stolen, was blue.
✓ Correct: The car that was stolen was blue.
Note: Essential defining clauses take NO commas.
Mistake 3: Omitting relative pronoun when it is the Subject
❌ Incorrect: The man lives next door is nice.
✓ Correct: The man who lives next door is nice.
Note: Cannot omit relative pronoun when it acts as the subject of the clause.

❓ Frequently Asked Questions (FAQ)

Q1: How do I quickly test if a clause is defining or non-defining?

Remove the clause! If the sentence still makes clear sense and identifies the noun, it was NON-DEFINING (use commas). If the sentence becomes vague/meaningless, it was DEFINING (no commas).

Q2: Why is "which" sometimes used to refer to an entire sentence?

In non-defining clauses, "which" can refer back to an entire previous clause: "He passed the test, WHICH surprised everyone" (which = the fact that he passed).

Q3: Can "whose" be used in both defining and non-defining clauses?

Yes! "The boy whose dog ran away" (defining) and "John, whose dog ran away, is sad" (non-defining).

1. Form & Structure

Defining vs Non-Defining Clauses Comparison Matrix

Defining Clause (Essential): The doctor who treated me was kind. (Which doctor? The one who treated me). NO COMMAS!

Non-Defining Clause (Extra Info): Dr. Smith, who treated me, was kind. (We already know his name!). COMMAS REQUIRED!

Use of THAT: "That" can replace who/which ONLY in Defining clauses! Never use "that" after a comma.

Omission of Relative Pronoun: Can omit who/which/that ONLY in Defining clauses when it acts as an OBJECT.

Example / Question	Positive / Short Answer	Negative / Short Answer
Defining: Essential info	The house that I built is big.	No commas & Can use "that"
Non-Defining: Extra info	My house, which I built in 2010, is big.	COMMAS required & CANNOT use "that"
Pronoun Omission	The movie (that) I watched was good.	Omit "that" because "I" is subject

2. Key Rules & Formation

Rule	Base / Standard Form	Applied Form
No "That" After Commas Rule	NEVER use "that" in a non-defining relative clause (after a comma)! Use who or which instead.	My brother, who lives in Hanoi (CORRECT) vs My brother, that lives in Hanoi (WRONG)
Comma Rules for Extra Information	Use commas before and after non-defining clauses because they add non-essential extra detail.	Paris, which is beautiful, is expensive.
Object Pronoun Omission Rule	You can omit who/which/that ONLY in defining clauses when followed by Subject + Verb.	The car (which) I bought

3. Practical Usage & Examples

1. Identifying specific people or objects clearly

Distinguish one item out of many possibilities in defining clauses.

The student who sits at the front gets top marks.

2. Adding interesting background information seamlessly

Enrich your writing with details separated by commas.

My grandmother, who is 85 years old, still swims every day.

3. Connecting thoughts without repeating nouns

Build complex, fluent sentences.

I bought a camera, which broke after two days.

💡 Common Mistakes & Memory Tips

Mistake 1: Using "that" after a comma in non-defining clauses
❌ Incorrect: My mother, that is a doctor, works hard.
✓ Correct: My mother, who is a doctor, works hard.

Note: Never use "that" in non-defining clauses with commas.

Mistake 2: Putting commas around essential defining clauses
❌ Incorrect: The car, that was stolen, was blue.
✓ Correct: The car that was stolen was blue.

Note: Essential defining clauses take NO commas.

Mistake 3: Omitting relative pronoun when it is the Subject
❌ Incorrect: The man lives next door is nice.
✓ Correct: The man who lives next door is nice.

Note: Cannot omit relative pronoun when it acts as the subject of the clause.

❓ Frequently Asked Questions (FAQ)

Q1: How do I quickly test if a clause is defining or non-defining?

Remove the clause! If the sentence still makes clear sense and identifies the noun, it was NON-DEFINING (use commas). If the sentence becomes vague/meaningless, it was DEFINING (no commas).

Q2: Why is "which" sometimes used to refer to an entire sentence?

In non-defining clauses, "which" can refer back to an entire previous clause: "He passed the test, WHICH surprised everyone" (which = the fact that he passed).

Q3: Can "whose" be used in both defining and non-defining clauses?

Yes! "The boy whose dog ran away" (defining) and "John, whose dog ran away, is sad" (non-defining).

Relative Clauses

1. Form & Structure

Defining vs Non-Defining Clauses Comparison Matrix

2. Key Rules & Formation

3. Practical Usage & Examples

1. Identifying specific people or objects clearly

2. Adding interesting background information seamlessly

3. Connecting thoughts without repeating nouns

4. Signal Words & Usage Context

💡 Common Mistakes & Memory Tips

❓ Frequently Asked Questions (FAQ)

Q1: How do I quickly test if a clause is defining or non-defining?

Q2: Why is "which" sometimes used to refer to an entire sentence?

Q3: Can "whose" be used in both defining and non-defining clauses?

Relative Clauses

1. Form & Structure

Defining vs Non-Defining Clauses Comparison Matrix

2. Key Rules & Formation

3. Practical Usage & Examples

1. Identifying specific people or objects clearly

2. Adding interesting background information seamlessly

3. Connecting thoughts without repeating nouns

4. Signal Words & Usage Context

💡 Common Mistakes & Memory Tips

❓ Frequently Asked Questions (FAQ)

Q1: How do I quickly test if a clause is defining or non-defining?

Q2: Why is "which" sometimes used to refer to an entire sentence?

Q3: Can "whose" be used in both defining and non-defining clauses?

Other Clauses lessons

Practice Exercises

Relative clauses: Defining and non-defining Part 1

Relative clauses: Defining and non-defining Part 2

Relative clauses: Defining and non-defining Part 3