听力原文： Mr. Smith was a wealthy industrialist, but he was not satisfied with life. He did not sleep well and his food did not agree with him. This situation lasted for some time. Finally, after several sleepless nights, he decided to go to see his doctor. The doctor advised him to go abroad to change condition. But Mr. Smith was afraid that he was not good at foreign language. The doctor told him that he could talk a little less and gave him four pieces of advice: go on a voyage, take plenty of exercise, try to re- duce his weight and avoid rich food.
Mr. Smith went to French. But he did not know French, and had to communicate through body movements. He joined in a physical training course. The teacher made him shake his knees, his arms, his neck and his head rapidly. He had to lie on the ground and raise his right and left legs. After a time his body grew hard and firm. He forgot his company and the importance of raising the level of production. He even began to notice the green trees and the lovely birds.
Finally he returned home. But unfortunately his improvement was only temporary. Soon he was a normal business man again, worried about his company, his savings, his advancement in a technological society,and things in general.
Why did Mr. Smith go to see his doctor？

A. Because he had little to eat.
Because he was seriously ill.
C. Because he was afraid of sleeping at night.
D. Because he didn't feel well.