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Did you know?
The familiar sounds of your heart are made by the heart's valves as they open and close.
Did you know?
Vaccines prevent between 2.5 and 4 million deaths every year.
Did you know?
During the twentieth century, a variant of the metric system was used in Russia and France in which the base unit of mass was the tonne. Instead of kilograms, this system used millitonnes (mt).
Did you know?
In the United States, an estimated 50 million unnecessary antibiotics are prescribed for viral respiratory infections.
Did you know?
Urine turns bright yellow if larger than normal amounts of certain substances are consumed; one of these substances is asparagus.