阅读下面的短文，根据短文内容回答问题。 Now and then we all get ill. Then we usually go to see a doctor. Doctors know a lot about what makes us ill. They may give us something to take. The medicine often makes us well again. But sometimes the doctor's medicine doesn't work. A sick person does not get well. The pain will not go away. This happened to one man. He was in hospital, but he was not getting well. Then he found a new 'doctor' inside himself. This new 'doctor' was his own sense of humor (幽默感). He saw funny films. He read funny books. And something wonderful happened. Laughing took away his pain. Then he was able to sleep and rest. His own happy feeling helped him to feel well again. He said laughing was his best ' medicine'. His doctor thought so, too. Another  man was also ill, and he had a terrible pain in his back. The doctors could not stop it from hurting. So the man began to 'Picture' his pain. In his head he 'drew ' a picture of a dog. He imagined it as a real dog. And he made friends with the dog. And his pain went away! These stories may surprise you. But more and more people are getting well in this way. So visit the 'doctor' inside your own head and you can stay happy and well. 1. Does medicine always work? ________________________________ 2. How many sick men are mentioned(提及) in this passage? ________________________________________ 3. Who was  the first sick man's new 'doctor'? ____________________________________________ 4. Who made the second sick man well again, the doctor or the 'dog' in his head? __________________________________________ 5 .Why does the writer ask us to visit the 'doctor' inside our head? _____________________________________________