阅读理解。
There is an English saying:“1._________.” Until recently, few people took the saying seriously.
Now, however, doctors have begun to look into laughter and the effects it has on the human body.
2. ________
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. 3.__________. If laughter exercises the body, it must be
beneficial（有益的）.
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.4._________.
5.__________. They have found that even if their patients do not really feel like laughing, making
them smile is enough to produce beneficial effects similar to those caused by laughter.
A. Laughter can prolong（延长）one’s life.
B. 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.
C. The reason why laughter can reduce pain seems to be that it helps to produce a kind of chemicals
in the brain which diminish (减少) both stress and pain.
D. 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.
E. Although laughter helps cure the disease, doctors still can not put this theory into clinic practice.
F. Laughter is the best medicine.
G. They have found that laughter really can improve people’s health
)，该梁计算跨度l0=7200mm，跨中计算所需的纵向受拉钢筋为4
25。