Feel tired lately? Has a doctor said he can't find anything wrong with you? Perhaps he sent you to a hospital, but all the advanced equipment there shows that there is nothing wrong with you. Then , consider this: you might be in a state of sub - health  . Sub - health, also called the third state or gray state, is explained as a borderline state between health and disease. According to the survey by the National Health Organization, Over 45 percent of sub - healthy people are middle-aged or elderly. The percentage is even higher among people who work in management positions as well as students around exam week. Symptoms  include a shortage of energy, depression, slow reactions, insomnia  and poor memory , Other symptoms include shortness of breath, sweating and aching in the waist and legs. The key to preventing and recovering from sub - health, according to some medical experts, is to form good living habits, ale mate work and rest, exercise regularly, and take part in open air activities. As for meals, people are advised to eat less salt and sugar . They should also eat more fresh vegetables, fruits, fish because they are rich in nutritional elements - vitamins and trace elements - that are important to the body. Nutrition experts point out that it is not good to eat too much at one meal because it may cause unhealthy changes in the digestive tract  . They also say that a balanced diet is very helpful in avoiding sub - health. The key to preventing you from falling into a state of sub health is to  _  .
keep on working regularly go to sleep a bit earlier form good living habits take medicine if necessary
Question: Feel tired lately? Has a doctor said he can't find anything wrong with you? Perhaps he sent you to a hospital, but all the advanced equipment there shows that there is nothing wrong with you. Then , consider this: you might be in a state of sub - health  . Sub - health, also called the third state or gray state, is explained as a borderline state between health and disease. According to the survey by the National Health Organization, Over 45 percent of sub - healthy people are middle-aged or elderly. The percentage is even higher among people who work in management positions as well as students around exam week. Symptoms  include a shortage of energy, depression, slow reactions, insomnia  and poor memory , Other symptoms include shortness of breath, sweating and aching in the waist and legs. The key to preventing and recovering from sub - health, according to some medical experts, is to form good living habits, ale mate work and rest, exercise regularly, and take part in open air activities. As for meals, people are advised to eat less salt and sugar . They should also eat more fresh vegetables, fruits, fish because they are rich in nutritional elements - vitamins and trace elements - that are important to the body. Nutrition experts point out that it is not good to eat too much at one meal because it may cause unhealthy changes in the digestive tract  . They also say that a balanced diet is very helpful in avoiding sub - health. The key to preventing you from falling into a state of sub health is to  _  .
A. keep on working regularly
B. go to sleep a bit earlier
C. form good living habits
D. take medicine if necessary
Answer: