题目内容：

    Many diseases and medical conditions are caused by things out of our control. Doctors urge us to eat healthy foods, get exercise, stop smoking and limit our alcohol intake. 1.    And it is free and easy. Smile!

When we smile, the brain wiring gets altered. The chemicals that are released are more positive. Smiling is a first step in fighting physical and emotional stress and its sometimes harmful effects on human health.

The main cause of heart attacks and strokes are blockages in blood vessels (血管).2.The most common reason for these blockages is a build-up of fatty deposits on the inner walls of the arteries (大动脉). When we feel stressed or under pressure, our body releases many natural hormones (荷尔家) including adrenaline and cortisol. When we are stressed for a long period, these stress hormones are ever-present in our bodies. And that, medical researchers warn, may lead to health problems.

3. However, they claim that when people are stressed for long periods of time, they may not make the best decisions about what to eat. They may overeat, smoke or drink too much alcohol. They may not get enough exercise or sleep. And all of these can lead to health problems.

Dr. Choctkalingam says a smile may be one way to help. He tells his patients to smile 20 times an hour. To some, that might seem like a lot of smiling. Or some might even feel foolish . . . smiling for seemingly no reason. 4. It is not invasive (侵入的) like a surgical operation. It is free and it has no bad side effects.

“Once we smile, we are relaxed. This relaxation directly lowers blood pressure, improves sugar levels in the blood. 5. .”

And it just may provide a little extra protection to everyone^ heart health.

A.But a smile does not involve drugs.

B.But there is something else we can do.

C.Experts say we can control and even prevent them.

D.These prevent blood from flowing to the heart or the brain.

E.And they are the number one cause of death around the world.

F.If we are smiling, we are breaking that link between stress and health.

G.Researchers say the link between stress and heart disease is still unclear.