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Author Question: Robert has played the harmonica for many years and is quite good at it. He finds that when he plays ... (Read 349 times) |
The immune system needs 9.5 hours of sleep in total darkness to recharge completely.
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.
Excessive alcohol use costs the country approximately $235 billion every year.
Though the United States has largely rejected the metric system, it is used for currency, as in 100 pennies = 1 dollar. Previously, the British currency system was used, with measurements such as 12 pence to the shilling, and 20 shillings to the pound.
Vaccines cause herd immunity. If the majority of people in a community have been vaccinated against a disease, an unvaccinated person is less likely to get the disease since others are less likely to become sick from it and spread the disease.