Form and relative pronouns
Non-defining relative clauses add extra, non-essential information about a noun that is already identified. They are always enclosed in commas.
| Pronoun | Refers to | Example |
|---|---|---|
| who | People | My teacher, who has lived in London, speaks perfect English. |
| which | Things / animals | The book, which I bought last week, is excellent. |
| whose | Possession (people/things) | My neighbour, whose dog barks all night, has moved away. |
| where | Places | Paris, where she grew up, is a beautiful city. |
| when | Times | August, when it's hottest, is the worst time to visit. |
Key rules
| Rule | Correct | Wrong |
|---|---|---|
| Commas are required | My car, which is blue, is very fast. | ✗ My car which is blue is very fast. |
| Cannot use "that" | The Eiffel Tower, which was built in 1889… | ✗ The Eiffel Tower, that was built in 1889… |
| Pronoun cannot be omitted | My friend, who I met in Paris, called me. | ✗ My friend, I met in Paris, called me. |
"Which" referring to a whole clause:
In non-defining clauses, which can refer to the entire previous idea: "He passed the exam, which surprised everyone." (= the fact that he passed surprised everyone)
Defining vs Non-defining relative clauses
| Feature | Defining | Non-defining |
|---|---|---|
| Purpose | Identifies which person/thing | Adds extra information (noun already identified) |
| Commas | No commas | Commas required |
| "that" | ✓ Can use "that" | ✗ Cannot use "that" |
| Omit pronoun | ✓ Can omit when object | ✗ Cannot omit pronoun |
| Removable? | ✗ Changes meaning if removed | ✓ Can be removed without changing core meaning |
| Example | The woman who called was your boss. (= which woman — essential) |
Maria, who called yesterday, is my boss. (= extra info about Maria) |
Exercises
Defining or non-defining? Choose the correct option.
1. "The book ___ I told you about is amazing." — The listener doesn't know which book yet.
2. "Hamlet, ___ Shakespeare wrote in 1600, is a famous tragedy." — Hamlet is already identified.
3. Which sentence is correct non-defining usage?
4. "He forgot his passport, ___ meant we had to go back." — "which" refers to the whole situation.
5. In the sentence "My father, ___ I respect greatly, is a doctor" — can the pronoun be omitted?