A daily dose of laugher may be good for the heart because it makes blood vessels work more

A daily dose of laugher may be good for the heart because it makes blood vessels work more efficiently. Depression,【C1】______the other hand,can raise the risk of dying from heart failure,a separate study found. The two studies,【C2】______at a meeting of the American College of Cardiology in Florida, show how psychological factors can【C3】______a persons health. " We dont recommend that you laugh and not exercise,【C4】______we do recommend that you try to laugh on regular basis. Thirty minutes of exercise three times a week and fifteen minutes of laugher on a daily【C5】______is probably good for the vascular(脉管)system,"said Doctor Michael Miller. Miller and his colleagues at the school【C6】______ two movies, one humorous,【C7】______stressful, to twenty healthy volunteers and tested the function of their blood vessels. The researchers specifically looked at the lining of the vessels and found that blood【C8】______ was reduced in fourteen of the twenty volunteers after stressful movie cuttings. But blood flowed more freely in nineteen of the twenty volunteers【C9】______ they laugh at fun movie segments. Average blood flow increased 22% during laughter,and【C10】______ 35% during mental stress,the researchers told the meeting.

【C1】

A．at

B．on

C．in

D．by

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