Defining relative clauses In a defining relative clause, we include information that identifies or classifies people (1) and things (2). The meaning of the sentence is not complete without the defining relative clause. I Do you remember the woman who used to work in the bookshop? She's a teacher now. 2 Do you have a thing that measures temperature?-You mean a thermometer? Sorry, I don't. We often use (that) at the beginning of a defining relative clause instead of the object (3) or the object of a preposition (4). We usually use (that) after noun phrases containing superlatives (5) or quantifiers (6). 3 I brought the dictionary. Maria wanted it.I brought the dictionary (that) Maria wanted. 4 The film is "Twins' He's talking about it. The film (that) he's talking about is "Twins. 5 Ir's the best film (that) I've seen in years. He was the worst teacher (that) I had at school. 6 There's a lot (that) I don't know about computers. Every person (that) we met had a cold. We can also begin defining relative clauses with who, whom and which. 7 I don't know anyone who/whom I can trust. • There are two rules which you must always obey.