1. Lee contributed fifty dollars, but he wishes he could contribute ________.

2. It is gravity ________ objects toward the earth.

3. Using a globe can be ________ it is educa-tional.

4. “Forty-niners” ________ to California for gold in 1848.

5. ________ many of the designs for the new capital were considered lost forever, Benjamin Banneker helped reproduce the original plans.

6. The wheel, ________ has remained important for 4,000 years, is one of mankind’s first inventions.

7. ________ has improved a lot since she started her new job.

8. I know ________ a different way to get there but I like this one.

9. Physical fitness exercises can cause injuries ________ the participants are not careful.

10. Although solar energy is cheaper than oil, ________ have advantages as well as disadvantages.

11. Birds head south to warmer climates when ________.

12. If one of the participants in a conversation wonders ________, no real communication has taken place.

13. He________looked forward to the new venture.

14. The juice contained in the brittles of the nettle causes an intense itch when ________ a persons skin.

15. Everyone ________ albinos has a certain amount of pigment in the skin to add color.

16. In the Morrill Act, Congress granted federal lands to the states ________ agricultural and mechanical arts colleges.

17. Ancient people believed that ________ with a sun and a moon rotating around it.

18. Technically, glass is a mineral and ________.

19. Unlike the earth, which rotates once every twenty-four hours, ________ once every ten hours.

20. They were happy the train arrived on time and ________.