Answer:
1. A university is a college <u>where</u><u> many subjects are studied.</u>
2. Cable television, <u>which</u><u> was originally used to bring in distant stations</u>, provides many types of specialized programming.
3.Juke boxes <u>that</u><u> used to play a song for a dime</u> now cost much more.
4. Help came at a time<u> </u><u>when</u><u> Stan needed it most</u>.
5. John Chapman, <u>who</u><u> was nicknamed Johnny Appleseed</u>, planted apple seeds in Ohio, Indiana, and Illinois.
6. Hummingbirds are tiny birds <u>that</u><u> are less than three inches long</u>.
7. The Irish wolfhound, <u>which</u><u> is a hunting dog</u>, is the tallest breed of the species.
8. The diver <u>whose</u><u> turn it was </u>waved to the crowd.
9. Hurricanes are tropical cyclones <u>that</u><u> have wind speeds of up to 150 miles per hour.
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10. Abraham Lincoln, <u>who</u><u> moved from Illinois to Washington</u>, grew up in Kentucky.
11. The Arabian Nights is a collection of stories <u>that </u><u>have been passed down from one generation to the next</u>.
12. Is Natalie the keyboard player <u>whom</u><u> you asked to join the band</u>?
13. I need to edit this report<u> </u><u>that </u><u>I am writing</u>.
14. Many students <u>who</u><u> bring their lunches to school </u>buy milk in the cafeteria.
15. Athens, <u>which</u><u> is the capital of Greece</u>, is believed to have been named after Athena.
Explanation:
The underlined phrases are the adjective clauses. They perform the job of describing the noun in each sentence. The word in BOLD would be the relative pronoun.