1. After Eli Whitney invented the cotton gin in 1793, the cotton market had boomed.

2. Certain bats used their own sound to locate food and to avoid obstacles as they fly at night.

3. Professional medical schools were organized in the 1780`s and surgery made major gains when anesthetics was perfected in the 1840`s.

4. The name “vitamine” is proposed by Casimir Funk, who suspected that these substances were essential for life.

5. The hot dog`s popularity begun in St Louis in 1833 when a sausage peddler named Feuchtwanger slipped one of his franks into a bun.

6. During the early part of the Colonial period, living conditions were hard, and people have had little time for reading and studying.

7. Migraines were usually worse than tension headaches and can be so intense as to cause vomiting and vision problems.

8. Tea did not become popular in Europe until the mid-17th century when it has been first imported to England and Holland.

9. The term Neanderthal man was used to describe widely dispersed populations that lived between 110,000 and 35,000 years ago.

10. From the vibrations of the web, was set up by a trapped animal, a spider learns much about the nature of its catch.

11. The Augustinian monk, Gregor Mendel, performed many experiments which have won him the title of “Father of Genetics”.

12. The body temperature of a cold-blooded animal is varying with that of its environment and may reach a temperature of above 98º in the sun.

13. Both bowling and ice-skating was introduced by the Dutch who colonized the New World in the 1600`s.

14. Statistics show that the greatest number of B.A. degrees in recent years has been conferring in the fields of business management, education, and social sciences.

15. Penicillium is one of the many molds that produces the antibiotics used to control disease.

16. Before the Industrial Revolution come to America, the vast majority of the population lived in rural areas.

17. The process of making Egyptian sun-dried mud bricks are much the same today as it was in prehistoric times.

18. Forgetting, something usually mean an inability to retrieve the material that is still stored somewhere in the memory.

19. The electrical activity of the brain causes the transmission of brain waves that can be recorded and interpreted in terms that explains the types of mental activity.

20. It was only after 1815 that a distinctive American literature had begun to appear with writers like Washington Irving and James Fenimore Cooper.