We use relative clauses to join two sentences or to give more information about something. The relative clauses can be:
•Defining – They provide essential information to understand which noun we are talking about. We need the relative clause.
👉 The girl who talked to you is pregnant (if we omit “who talked to you” we don’t know which girl is pregnant)
•Non-defining – They provide extra information about something. We don’t need this information to understand the sentence.
👉 I live in London, which has some fantastic parks (if we omit “which has some fantastic parks” we still understand)
Defining relative clauses
These relative clauses are never separated by commas. In these sentences we can use the following relative pronouns:
•Who (for people) 👉 I’m looking for a secretary who can use a computer well
•Which (for things) 👉 She has a car which is older than you
•Whose (“cuyo, cuya…”) 👉 The dog whose owner lives next door is over there
•Where (for places) 👉 I live in the city where I study
•When (for times) 👉 The summer when I graduated from university was long and hot
•Whom (for people as the object of a clause) 👉 This is Peter whom you met last year
•Why (after “the reason”) 👉 You were the reason why I came to live here
•That (instead of who, whom or which) 👉 The girl that lives next door had an accident
If who, which or that are the object of the clause, they can be omitted
👉 The book which you gave me is amazing → The book you gave me is amazing
💡 “gave” is the verb, “you” is the subject, “which” is the object
👉 The homework that I have to do is a nightmare → The homework I have to do is a nightmare
💡“have” is the verb, “I” is the subject, “that” is the object
👉 The girl who I met at the party is gorgeous → The girl I met at the party is gorgeous
💡 “met” is the verb, “I” is the subject, “who” is the object
Non-defining relative clauses
These relative clauses are always separated by commas. In these sentences we can use the following relative pronouns:
•Who (for people) 👉 My boss, who is very nice, lives in Manchester
•Which (for things) 👉 My bicycle, which I’ve had for more than ten years, is falling apart
•Whose (“cuyo, cuya,…”) 👉 Peter, whose dog was sick, was really sad
•Where (for places) 👉 I’m going to Oviedo, where my mother lives
•When (for times) 👉 We’ve discussed this already, when she was not around
•Whom (for people as the object of a clause) 👉 I’ll work with Carl, whom I haven’t talked to for a long time
Careful! We cannot omit the relative pronoun in Non-defining clauses!!