1. Beriberi had long been a common and a seriously disease in parts of the world where published rice was the staple food.

2. Gold is present under the sea in so minute concentrations that no method  has yet been devised to extract it profitably.

3. Because the outer surface of an airplane is made almost entirely of metal, lightning currents penetrate seldom to the interior or affect passengers.

4. Scientists believe that the pupil response is too sensitive that it can detect differences too slight to be expressed verbally.

5. An animal has to eat great quantities of plants in order to extract calories enough to sustain itself.

6.A tornado travels usually in a north easterly direction, at a speed in the range of 35 to 45 miles an hour, and is preceded by heavy rain.

7. By 1880, A.A. Michelson measured actually the speed of light, laying some of the major foundations for the later work of Albert Einstein.

8. The blankets of fog that cover often coastlines and valleys are really ground-level clouds which are usually composed of minute water droplets.

9. Exhaust emissions have become very severe in certain urban areas that dead trees along the freeways have been replaced with plastic replicas.

10. When the eggs of the Nile crocodile are close to hatching, the young within make piping calls which are too loud that they can be heard from several meters.

11. The multi-storied skyscraper, developed by Louis Sullivan, with its iron or steel framework reflected some of America`s industrial great achievements in the last half of the 19th century.

12. An American college typically offers a blend of naturally and social sciences and humanistic studies.

13. Unlike oxygen, which is chemical changed by our bodies into carbon dioxide, nitrogen is merely exhaled back into the air.

14. The Grand Canyon is too dry that only isolated juniper trees and low scrub freckle the surface of the cliffs and the rock strata.

15. an assembly of frogs in a typical swamp can create so a noise that a human voice has to shout to make itself heard.

16. When President Franklin Roosevelt was elected to a third term in 1940 the tradition of a two-terms office was broken.

17. Judging from fossil skeletons, the first mammal who lived in dinosaur-dominated forests must have been long-tailed, smell, and pointed-nosed.

18. In a ten-years period between 1890 and 1900 over 220,000 patents were issued by the government for new inventions in the United States.

19. Because the snake can absorb the sun`s rays direct, its food requirement is small and consists of a dozen or so meals a year.

20. Beginning in the mid-1940`s, plant breeders developed new strains of wheat that gave higher substantially yields per acre.