The Grammar Lab: Relative Clauses

Lesson 11: Defining vs. Non-Defining

Essential vs. Extra

A Relative Clause adds information about a noun. The most important rule is about Commas.

🔹 Defining (Essential): Tells us which one. No commas. (គ្មានក្បៀស)
🔹 Non-Defining (Extra): Just adds detail. Needs commas. (មានក្បៀស)

Defining Essential

Identifies exactly who or what we are talking about. If you remove it, the sentence loses meaning.
Note: Can use "That".

The man who called is my dad.	(Which man?)
The car that hit me was red.	(Which car?)

Non-Defining Extra Info

Adds interesting information, but we already know who/what it is.
Note: NEVER use "That". Commas are required.

My dad, who called, is angry.	(We know it's dad)
Paris, which is big, is nice.	(Everyone knows Paris)

The "That" Trap ⚠️

You cannot use "That" after a comma.

✅ The book that I bought...	(Defining)
❌ My book, that is old...	(Wrong!)
✅ My book, which is old...	(Correct)

Meaning Check

Click to see how commas change the meaning.

My brother who lives in USA...No Commas

My brother, who lives in USA,...With Commas

The players who were tired...No Commas

The players, who were tired,...With Commas

Quick Check

1. London, _____ is in England, is big.

2. The man _____ stole my bag ran away.

3. Choose the correct punctuation: