It is reported that over 300 million people in China are suffering from nearsightedness(近视). As more children have got eye trouble, their parents hope to cure the disease by medicine, equipment or by correcting the way children read and sit. But in fact the care given to one's eyes should start with the exercise on one' s feet. Three methods on how to protect eyes are as follows: Firstly, don't fasten your shoes too tightly. Try wearing loose socks or walking barefooted at home. When traveling, try wearing cloth shoes so as to make blood circulation (循环) easier. Secondly, walking on tiptoes will help improve one's eyesight, and prevent nearsightedness. Figures show that few ballet (芭蕾舞) performers are nearsighted. Thirdly, rope skipping also does good to one's eyesight. When skipping the rope, one has to react quickly, which excites the brain as well as the eyes. It will also help make one grow taller. Besides foot exercises, it is good to pull one's ears. Pulling the ears 20 times is found to be an effective way to reduce the pressure on one's eyes soon. To cure nearsightedness, people don't usually______.