Laughter
There is an old saying in English: "Laughter is the best medicine". Untilrecently， few people took the saying very seriously. Now， however， doctors havebegun to investigate laughter and the effects it has on the human body. Theyhave found evidence that laughter really can improve peoples health.
Tests were carried out to study the effects of laughter on the body. Peoplewatched funny films， while doctors checked their heart rate， blood pressure，breathing and muscles. It was found that laughter has similar effects tophysical exercise. It increases blood pressure， the heart rate and the rate ofbreathing; it also works several groups of muscles in the face， the stomach， andeven the feet. If laughter exercises the body， it must be beneficial.
Other tests have shown that laughter appears to be capable of reducing theeffect of pain on the body. In one experiment doctors produced pain in groups ofstudents who listened to different radio programs. The group which tolerated thepain for the longest time was the group which listened to a funny program. Thereason why laughter can reduce pain seems to be that it helps to produceendorphins (内啡肽) in the brain. These are natural chemicals which diminish bothstress and pain.
There is also some evidence to suggest that laughter helps the bodysimmune system， that is， the system which fights infection. In an experiment， onegroup of students watched a funny video while another group served as thecontrol group - in other words， a group with which to compare the first group.
Doctors checked the blood of the students in both groups and found that thepeople in the group that watched the video had an increase in the activity oftheir white blood cells， that is， the cells which fight infection.
As a result of these discoveries， some doctors and psychiatrists (精神病学家) inthe United States now hold laughter clinics， in which they try to improve their
patients condition by encouraging them to laugh. They have found that even iftheir patients do not really feel like laughing， making them smile is enough toproduce beneficial effects similar to those caused by laughter.
36 We learn from the first paragraph that laughter
A is good for ones health.
B is related to some illness.
C has been investigated long since.
D has no effect on the body.
37 Doctors have found that laughter
A keeps down blood pressure.
B has similar effects to physical exercise.
C decreases the heart rate.
D increases stress.
38 Which of the following statements is NOT true of laughter， according tothe passage?
A It reduces pain.
B It exercises the body.
C It improves the bodys immune system.
D It can cure cancer.
39 Ina laughter clinic， doctors
A laugh at their patients.
B encourage their patients to laugh.
C smile when they dont feel like laughing.
D never stop laughing.
40 The writers attitude towards laughter is
A critical.
B doubtful.
C positive.
D negative.
36. A 37. B 38. D 39. B 40. C