[单项选择]Basically, there are three types of fatigue: physical, pathological (由疾病引起的), and psychological. As you might suspect, each differs significantly from the others.
When you exercise your body you produce waste products. Muscles, for example, discard lactic acid (乳酸) into the blood; cells dump in carbon dioxide. When these wastes reach a certain level in the blood, the brain is notified and your activity level drops. Excess wastes in the muscles may produce soreness. If the blood of a physically fatigued animal is injected into a rested animal, it will produce fatigue. The solution to this type of fatigue is simple - rest. That should revive you; if it doesn’t, another cause should be sought.
Have you ever become involved in so many activities that you had to be in two places at once This is what happens when your body has a disease. The cells are overtaxed and cannot keep up with both fighting the disease and keeping you active. The result is fatigue. Some communicable di
A. Some pathological fatigue is good for people.
B. Everyone is vulnerable to pathological fatigue.
C. Pathological fatigue needs no medical attention.
D. Pathological fatigue harms people psychologically only.