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Astigmatism is the most common vision problem. It may accompany nearsightedness or farsightedness. It is usually caused by an irregularly shaped cornea, but sometimes it is the result of an irregularly shaped lens. Either type can be corrected by eyeglasses, contact lenses, or refractive surgery.
Pope Sylvester II tried to introduce Arabic numbers into Europe between the years 999 and 1003, but their use did not catch on for a few more centuries, and Roman numerals continued to be the primary number system.
The top 10 most important tips that will help you grow old gracefully include (1) quit smoking, (2) keep your weight down, (3) take supplements, (4) skip a meal each day or fast 1 day per week, (5) get a pet, (6) get medical help for chronic pain, (7) walk regularly, (8) reduce arguments, (9) put live plants in your living space, and (10) do some weight training.
Although puberty usually occurs in the early teenage years, the world's youngest parents were two Chinese children who had their first baby when they were 8 and 9 years of age.
The word drug comes from the Dutch word droog (meaning "dry"). For centuries, most drugs came from dried plants, hence the name.