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People seeking to stay healthy can get their exercise in small increments of just a few minutes at a time, according to new guidelines issued by the American government that again encourage a largely sedentary nation to start moving. The guidance from a committee appointed by the Department of Health and Human Services of America does away with the official government position that physical activity should occur at least 10 minutes.

"Current evidence shows that the total volume of moderate-to-vigorous physical activity is related to many health benefits; bouts of a prescribed duration are not essential," the committee of health experts wrote.

Thomas Allison, director of sports and exercise cardiology, said short bouts of exercise are valuable to break up long stretches of sitting. But research shows that multiple short sessions should involve similar energy expenditure to have the same impact as one longer session, or additional time moving will be needed, he said.

For adults to stay healthy, the new guidelines call for 150 to 300 minutes of moderate-intensity exercise or 75 to 150 minutes of vigorous-intensity physical activity each week, along with at least two days a week of muscle-strengthening exercises.

The guidelines cite walking briskly at 3.9 to 6.4 kilometers per hour, playing volleyball or raking leaves as moderate-intensity activity. Vigorous-intensity exercise includes jogging or running, carrying heavy groceries or taking a strenuous fitness class, the panel said. Some workouts, such as swimming and cycling, can fall into either category, depending on the effort expended.

1.What’s the Chinese meaning of the underlined word “sedentary”?

A 强大的.

B 久坐的.

C 运动的.

D 富有的.

解析：选B。词义猜测题。美国政府新发布了一份指南是希望鼓励这个“久坐不动的”国家多动一动，故选B。

2.How long should physical activity occur according to the official government?

A At least 10 minutes.

B At least 20 minutes.

C Less than 10 minutes.

D Less than 20 minutes.

解析：选A。细节理解题。根据第一段最后一句...the official government position that physical activity should occur at least 10 minutes.可知政府认为运动应该至少持续10分钟，故选A。

3.What’s the effect of short bouts of exercise?

A To keep warm.

B To lose weight.

C To be more healthier.

D To break up long stretches of sitting.

解析：选D。细节理解题。根据第三段第一句Thomas Allison, director of sports and exercise cardiology, said short bouts of exercise are valuable to break up long stretches of sitting.可知短时间的小运动是很有用的，它们可以打断你的久坐行为，故选D。

4.How long should adults take moderate-intensity exercise each day according to the new guidelines?

A About 10 to 20 minutes.

B About 15 minutes.

C About 20 to 40 minutes.

D About one hour.

解析：选C。推理判断题。根据第四段For adults to stay healthy, the new guidelines call for 150 to 300 minutes of moderate-intensity exercise or 75 to 150 minutes of vigorous-intensity physical activity each week...可知，新的指南说，对于那些想保持健康的成年人，每周需要150至300分钟的中等强度锻炼，每天大约20至40分钟，故选C。

5.Which of the following belongs to moderate-intensity activity?

A Playing volleyball.

B Jogging.

C Running.

D Carrying heavy groceries.

解析：选A。细节理解题。根据最后一段第一句The guidelines cite walking briskly at 3.9 to 6.4 kilometers per hour, playing volleyball or raking leaves as moderate-intensity activity.可知中等强度活动包括：以3.9-6.4千米/小时的速度走路、玩排球或者扫落叶，故选A。