2. Doctor Jones, who is going through a midlife crisis, just bought a red car. The doctor who is going through a midlife crisis just bought a red car. What is the difference? Do not use commas if the adjective clause is necessary to identify the noun it modifies. (called : essential, restrictive, or identifying) Use commas if the adjective clause simply gives additional information and is not necessary to identify the noun it modifies. (called: nonessential, nonrestrictive, or nonidentifying)

3. 1. The vegetables that people leave uneaten are often the most nutritious. 2. Broccoli, which people often leave uneaten, is very nutritious. Another Example What is the difference? -Vegetables is nonspecific. To know which ones we are talking about, we must have the information in the adjective clause. Thus, the adjective clause is essential and requires no commas. -If, however, we eliminate vegetables and choose a more specific noun instead, the adjective clause becomes nonessential and does require commas to separate it from the rest of the sentence.nonessential

4. With commas 1. Mary Smith, who works night and day, is an excellent lawyer. 2. The Golden Gate Bridge, which spans the entrance to San Francisco Bay, is the longest bridge in the world. 3. Professor Wilson, who teaches English, is an excellent teacher. 4. The man (who, whom, that, Ø)I met teaches math. 5. I refuse to live in any house (that, which)Jack built. - If an adjective clause modifies a proper noun, we use commas. (1,2,3) - When we use commas, we may use (who, whom, which, whose, where, and when) but not (that). (1,2,3) - If no commas are used, we can use any relative pronoun and object pronouns may be omitted.(4,5)

5. The movies that I like best are filled with romance and comedy. Caramel de Lites, which are cookies sold by the Girl Scouts, contain 70 calories each. I left my son at the campus day-care center, which is available to all full-time students with young children.

6. Compare the meaning Students who want to use the free day-care center are invited to use it tomorrow. Students, who want to use the free day-care center, are invited to use the free day-care center. *The use of commas means that all of the students are invited to use the center, the adjective clause gives an additional information. *The lack of commas means that only some of the students are invited to use the center, the adjective clause is used to identify which students are invited.