Relative Clauses – Detailed Expressions; It is used to give extra information about the nouns in the main clause, without starting another sentence. A relative clause starts with a relative pronoun. who / that Subject or object pronoun for people That’s the woman who bought my house. which / that Subject or object pronoun for ANIMALS or THINGS The horse which Mary was riding is very friendly and beautiful. where Refers to a PLACE We found the wood where I used to go. when Refers to a TIME expression I will never forget the day when I graduated. whose POSSESSION