In Subordination with Adjective Clauses, we learned how an adjective clause functions like an adjective to modify a noun. In Relative Pronouns and Adjective Clauses, we focused on the roles played by the relative pronouns which, that, who, whom, and whose. Here we'll learn to distinguish between the two main types of adjective clauses: nonrestrictive and restrictive.
Nonrestrictive Adjective Clauses
An adjective clause set off from the main clause by commas is said to be nonrestrictive. Here's an example:
Old Professor Legree, who dresses like a teenager, is going through his second childhood.This who clause is nonrestrictive because the information in the clause doesn't restrict or limit the noun it modifies (Old Professor Legree). The commas signify that the adjective clause provides added, not essential, information. This practice is consistent with Comma Guideline #4: "Use a pair of commas to set off interruptions."
Restrictive Adjective Clauses
On the other hand, an adjective clause that is restrictive should not be set off by commas.
An older person who dresses like a teenager is often an object of ridicule.Here, the adjective clause restricts or limits the meaning of the noun it modifies (An older person). A restrictive adjective clause is not set off by commas.
So let's keep in mind two basic rules:
An adjective clause that can be omitted from a sentence without affecting the basic meaning of the sentence should be set off by commas.
An adjective clause that cannot be omitted from a sentence without affecting the basic meaning of the sentence should not be set off by commas.
Practice: Identifying Restrictive and Nonrestrictive Clauses
- Students who have young children are invited to use the free daycare center.
- I left my son at the campus daycare center, which is free to all full-time students.
- John Wayne, who appeared in over 200 movies, was the biggest box-office attraction of his time.
- I refuse to live in any house that Jack built.
- Merdine, who was born in a boxcar somewhere in Arkansas, grows homesick every time she hears the wail of a train whistle.
- My new running shoes, which cost more than a hundred dollars, fell apart during the marathon.
- I lent some money to Earl, whose house was destroyed in the flood.
- The thing that impresses me the most about America is the way parents obey their children.
- A physician who smokes and overeats has no right to criticize the personal habits of his patients.
- The beer that made Milwaukee famous has made a loser out of me.