A defining clause adds essential information to a sentence, it follows the noun/noun phrase it is defining.
- This is where I was born. (No other place)
Use relative pronouns (like who, which, that, etc) to start the defining clause.
- Use THAT / WHICH for objects.
- This is the book which/that you lent me.
- Use WHO / THAT for people.
- He is the man who/that shouted at me.
- Use WHERE for places.
- This is the bar where I met your mother.
- Use WHOSE for possession.
- That is the family whose house I love.
WHOM is used rarely in modern or informal English. It can be used for WHO as an object pronoun.
- To whom are you refering?
- More Modern / More Informal = Who are you refering to?
WHO, THAT, WHICH can be left out if the clause is the object of the sentence.
This is not possible with non-defining clauses.
- He's the teacher (who/that) I told you about.
- Who / That can be left out.
- He's the teacher who hit me.
- Who is the subject of the verb 'hit me' so cannot be left out.
A non-defining clause adds extra information to a sentence, it also follows the noun / noun phrase it refers to.
- Rome, which is the capital of Italy, is a great city.
If you are unsure if the clause is defining or non-defining, it can be tested by removing the clause. If the sentence still makes sense and conveys the main point, then it is a non-defining clause.
- Rome is a great city.
- The sentence makes sense.
- The place where I was born is great!
- If I remove the clause 'where I was born'..=> "The place is great.".
- This is ok grammatically, but what place are you describing? I don't know.
- The sentence no longer makes sense without the defining clause.
Non-defining clauses are extra information, so it is important to let the reader/listener know this.
- When writing we use commas:
- The film, which was in cinemas last year, is now available on Netflix.
- When speaking we lower our voice:
- "HER HUSBAND JEFF, who is a bus driver, IS REALLY NICE."
- NOTE how this is important with sentences such as these:
- My cousin who is American is very tall.
- I have more than one cousin, I am talking about the American one.
- My cousin, who is American, is very tall.
- I have just one cousin, she is tall and happens to be American too.
Use WHO for people.
- The man, who I had never seen before, gave me 10 dollars!
Use WHICH (NOT that) for objects.
- The car, which I had bought the year before, broke down.
Use WHERE for places.
- This fantastic stadium, where the first match was played, is about to be knocked down.
Use WHOSE for possession.
- The dog, whose owner lives there, attacked my cat.
WHO, WHICH, WHERE, WHOSE can not be left out.
- My dad, who lives in Florida, is called Rocky.
- NOT My dad, lives in Florida, is called Rocky
There is no need to repeat subject and object pronouns.
- Marvin, who lives nearby, is a fantastic player.
- NOT Marvin, who he lives nearby, is a fantastic player.
- The big book that was on the shelf has been stolen.
- NOT The big book that it was on the shelf has been stolen.