9. In bas-relief sculpture, a design projects very slightly from its background, as on some coins.

10. Alaska found the first years of its statehood costly because it had to take over the expense of services provided previously by the federal government.

11. With age, the mineral content of human bones decreases,thereby makingthem more fragile.

12. Not until Kentucky’s Mammoth Cave had been completely explored in 1972 was its full extent realized.

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

14. Written to be performed on a stage bare of scenery, Thornton Wilder’s play Our Town depicts life in a small New England community.

15.  There are many copper mines in the state of Arizona, a fact which contributes significantly to the state’s economy.