1. Anthropology is a science _____ anthropologists use a rigorous set of methods and techniques to document observations that can be checked by others.

2. The development of mechanical timepieces spurred the search for _____ with which to regulate them

3. Almost all economists agree _____ by trading with one another.

4. Because of the Aleuts’ constant exposure to cold weather, they have long recognized _____ .

5. The scholarly interest in perception stems largely from questions about the sources and validity of what _____ .

6. Paul Samuelson revolutionized _____ by presenting his students with the most advanced economic thinking at an introductory level.

7. Not until 1949 _______ Canada’s tenth province.

8. Steel magnate Andrew Carnegie used part of his wealth _______ more than 2,500 public libraries in Englishspeaking countries between 1881 and 1919.

9. The operating principles of the telephone are ______ they were in the nineteenth century.

10. ______ planes in flight between airports, air traffic controllers rely on radar.

11. Color and light, taken together, _____ the aesthetic impact of the interior of a building

12. If an act is rewarded many times, immediately and with strong reinforces, it will rapidly become _____.

13. Although both political parties wanted Dwight D. Eisenhower as their presidential nominee in 1952, he became a Republican candidate and _____.

14. _____ have a very keen sense of hearing, although most do not hear sounds audible to the human ear.

15. Sociologists have long recognized that social tension _____.