A、Lack of exercise. B、Lack of vitamin C. C、Their intestine functions slowly. D、Lack of massage of abdomen. C根据医生建议，适量运动、食用蔬菜和水果

W: Good morning. How are you feeling now? Do you still have pain in your chest?
M: No. There is no more pain, but I feel a little tight in my chest. I also feel dizzy when I stand up.
W: Your electrocardiogram shows that you have coronary heart disease. Your attack was brought on by an insufficient blood supply to the heart.
M: Will it happen again?
W: When you leave the hospital the doctor will give you instructions as to how to take care of yourself. If you follow the instructions carefully, perhaps it will not happen again.
M: That’s fine. Thank you. By the way, will you please tell me something about the diet I should follow?
W: Oh yes. It is important that you should pay special attention to your diet at your age. It should be light and low in fat. Your meals should be frequent but small in quantity. However, you must not forget that you should take some vegetables and plenty of fruit; not only to help to prevent constipation, but also supply all kinds of vitamins, especially Vitamin C.
M: I know I should eat more fruit and vegetable, because they will keep me from being constipated.
W: Older people often have constipation because their intestine has become sluggish. Besides some mild exercises, you’d better do some deep breathing and massage your abdomen every day. This will help to relieve your constipation.
M: I usually do a lot of things automatically. It has been my habit for many years. I don’t realize that I am already seventy years old.
W: Exercise and work are helpful. But don’t over-tire yourself. I notice you haven’t smoked since you entered the hospital. We hope you will not smoke when you go home.
M: I must determine to give up smoking and drinking. I know now that these habits are not good for me.
W: We suggest that you do some light work, have a happy outlook, listen to music, and avoid excitement and too much worry. And, above all, be careful not to stumble, because old people’s bones are fragile and get broken easily.
M: Thank you for your advice.
Questions 16-20 are based on the passage you have just heard.
16. What is the man’s disease?
17. According to the doctor, which of the following about the diet should the man NOT do?
18. What makes older people often have constipation?
19. How old is the man?
20. According to the doctor, what is the most important thing that the man should pay attention to?