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Author Question: The objective lens of a telescope has a focal length of 1.90 m. When viewed through this telescope, ... (Read 44 times) |
Ether was used widely for surgeries but became less popular because of its flammability and its tendency to cause vomiting. In England, it was quickly replaced by chloroform, but this agent caused many deaths and lost popularity.
The immune system needs 9.5 hours of sleep in total darkness to recharge completely.
Pregnant women usually experience a heightened sense of smell beginning late in the first trimester. Some experts call this the body's way of protecting a pregnant woman from foods that are unsafe for the fetus.
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.
Most childhood vaccines are 90–99% effective in preventing disease. Side effects are rarely serious.