1. _____ many copper mines in the state of Arizona, a fact which contributes significantly to the state’s economy.

2. In 1867 Russia sold Alaska to the United States, and in 1958 _____ the forty-ninth state.

3. The first explorer _____ California by land was Jedediah Strong Smith, a trapper who crossed the southwestern deserts of the United States in 1826.

4. Not until Kentucky’s Mammoth Cave had been completely explored in 1972 _____.

5. With age, the mineral content of human bones decreases, _____ them more fragile.

6. _____, The Yearling, won a Pulitzer Prize.

7. The colors of a rainbow _____ arranged in the same order.

8. Alaskan forests _____ five or six miles inland from the Pacific coast.

9. Adhesive, such as glue, tape, and gum, vary with the purpose _____ intended.

10. From her early teens _____

11. The windmill, which has been used for hundreds of years to pump water and grind grains, _____ redesigned to produce electricity.

12. Some procedures used for laboratory analysis of archaeological specimens are _____ procedures conducted in crime laboratories.

13. _____ were stones piled at intervals.

14. The skyscraper, _____,is an architectural form that originated in the United States.

15. In the textile industry, the term “gunny” refers to _____ burlap that is not of the best quality.