Identifying Nouns
Restrictive relative clauses identify nouns. They tell apart one person or thing from other people or things. They answer the question "which ones(s)?" Restrictive relative clauses express necessary information. They cannot be omitted without affecting the meaning of the sentence.
With a Relative Clause
Janice: Are your children in the school play?
Marco: Yes, the boy that's wearing the frog costume and the girl that's wearing a rabbit costume are mine. (The relative clause identifies who Marco's kids are and separates them from the other kids.)
Without a Relative Clause
Tanya: Are your children in the school play?
Lisa: Yes, the boy and the girl are mine.
Tanya: Which boy and girl?
(The meaning is incomplete because Marco's children have not been properly identified).
Restrictive relative clauses are used in definitions as well.
A locksmith is a person who makes and repairs locks and keys.
A penguin is a black and white bird which lives in the Antarctic.
Restrictive relative clauses are also used to provide information about a noun when it is first mentioned. If this information is new to the listener, the relative clause immediately identifies the noun. If the information has already been shared with the listener, the clause will remind the listener of the noun.
New Information
A girl who works with me got a scholarship to Harvard University!
Shared Information
Those are the shoes that are on sale.
Reducing Restrictive Relative Clauses
Subject relative pronouns + be are often omitted from restrictive relative clauses.
Full Form
Put on the jacket that/which is in your room.
Give the doll to the girl who/that is wearing a red sweater.
Reduced Form
Put on the jacket in your room.
Give the doll to the little girl wearing a red sweater.
Exercise
Please open the exercise to continue.