Relative clauses: who / which / that
We use the relative pronouns "who", "which", and "that" to join two ideas into one sentence and to give more information about a person or thing.
Who, which, and that: the basics
We use "who" for people and "which" for things or animals. "That" can replace both "who" and "which" in defining clauses, and it is very common in everyday English. The relative pronoun comes right after the noun it describes.
- •The woman who lives next door is a doctor.
- •I bought a phone which has a great camera.
- •This is the book that changed my life.
- •He's the teacher that helped me pass the exam.
Subject and object relative clauses
The relative pronoun can be the subject of its clause (it does the action) or the object (it receives the action). When it is the object, we can leave it out in defining clauses. We cannot leave it out when it is the subject.
- •The man who called you is my brother. (subject - cannot be omitted)
- •The film that we watched was boring. (object - can be omitted: The film we watched...)
- •She's the singer who I met at the concert. (object)
- •The keys which open this door are lost. (subject - cannot be omitted)
Defining vs. non-defining clauses
A defining clause gives essential information that we need to know which person or thing we mean, and it uses no commas. A non-defining clause adds extra, non-essential information and is separated by commas. Important: we do not use "that" in non-defining clauses, and we never drop the pronoun there.
- •The students who study hard usually pass. (defining - no commas)
- •My sister, who lives in Madrid, is a nurse. (non-defining - extra info)
- •This laptop, which I bought last year, still works perfectly.
- •Paris, which is the capital of France, is very beautiful.