A、By taking a shower. B、By drinking cold water. C、By cooling the skin. D、By sweating. D

Water is necessary for life and good health. We often forget this fact when we think about the other building blocks of life such as vitamins, minerals and proteins. We can live for many days without eating, but 2 or 3 days without water usually leads to death. New born babies are as much as 85 percent water. Women are about 65 percent water and men are about 75 percent. Women usually have less water than men because women in general have more fat cells, which hold less water than other cells. Water contains many different substances to keep us healthy and carries away waste materials. For example, blood is 83 percent water, muscles are 75 percent water, the brain is 74 percent, and bones are 25 percent. Water is also necessary for cooling the body on hot days. Water carries body heat to the surface of the skin where the heat is lost through sweat. Researchers say cold liquids cool us faster than warm liquids. They say, however, that cold sweet drinks do not work well because the sugar slows the liquid from getting into the blood stream. If we lose too much water we will become sick. A 10 percent drop in body water can cause the blood system to fall. A 15 percent to 20 percent drop usually leads to death. To replace what is lost, health experts say, grown person should drink about 2 liters of liquids each day, and more in hot weather. They say we also can get some of the water we need in the foods we eat.
19. Why do women have less water than men?
20. What is the function of water in human body?
21. How is body heat released in human?
22. Why aren’t cold sweet drinks so effective for cooling the body?