There is an English saying：“
Tests were carried out to study the effects of laughter on the body. People watched funny films while doctors checked their hearts, blood pressure, breathing and muscles. It was found that laughter has similar effects to physical exercise.
Other tests have shown that laughter appears to be able to reduce the effect of pain on the body. In one experiment doctors produced pain in groups of students who listened to different radio programs. The group that tolerated(忍耐) the pain for the longest time was the group which listened to a funny program.
| A．Laughter is the best medicine. |
| B．The reason why laughter can reduce pain seems to be that it helps to produce a kind of chemicals in the brain which diminish both stress and pain. |
| C．Although laughter helps cure the disease, doctors still can not put this theory into clinic practice. |
| D．Laughter can prolong one's life. |
| E．As a result of these discoveries, some doctors in the United States now hold laughter clinics in which they help to improve their patients' condition by encouraging them to laugh. |
| F．They have found that laughter really can improve people's health. |
| G．It increases blood pressure, the heart beating and breathing；it also works several groups of muscles in the face, the stomach and even the feet. |
