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Did you know?
Adult head lice are gray, about ? inch long, and often have a tiny dot on their backs. A female can lay between 50 and 150 eggs within the several weeks that she is alive. They feed on human blood.
Did you know?
Autoimmune diseases occur when the immune system destroys its own healthy tissues. When this occurs, white blood cells cannot distinguish between pathogens and normal cells.
Did you know?
The horizontal fraction bar was introduced by the Arabs.
Did you know?
About 3% of all pregnant women will give birth to twins, which is an increase in rate of nearly 60% since the early 1980s.
Did you know?
On average, someone in the United States has a stroke about every 40 seconds. This is about 795,000 people per year.