Non-Defining Relative Clauses Exercises

Non-defining relative clauses add extra, non-essential information about a noun that is already clear or unique. They are always set off by commas: "Shakespeare, who was born in Stratford-upon-Avon, wrote many famous plays." Since there is only one Shakespeare, the clause "who was born in Stratford-upon-Avon" is not needed to identify him — it simply adds an interesting fact. You could remove it entirely and the sentence would still be complete and clear.

Non-defining clauses have strict rules. First, always use commas — one before and one after the clause (or one before if it ends the sentence). Second, use who for people and which for things — never use that. "London, which is the capital of England, has over eight million people" is correct; "London, that is the capital" is wrong. Third, you can use "which" to refer to a whole clause: "He passed the exam, which surprised everyone" — here "which" refers to the entire fact of passing. Non-defining clauses are more common in written English and are regularly tested in Cambridge B2 First and C1 Advanced exams.