阅读理解。 America is a country on the move.

题目：

阅读理解。

     America is a country on the move. In unheard-of numbers, people of all ages are exercising their way to

better health. According to the latest figures, 59 percent of American adults exercise regularly-up 12 percent

from just two years ago and more than double the figure of 25 years ago. Even non-exercisers believe they

would be more attractive and confident if they were more active.

     It is hard not to get the message. The virtues of physical fitness are shown on magazine covers, postage

stamps, and television ads of everything from beauty soaps to travel books. Exercise as a part of daily life did

not catch on until the late 1960s when research by military doctors began to show the health benefits of' doing

regular physical exercises. Growing publicity (宣传) for races held in American cities helped fuel a strong

interest in the ancient sport of running. Although running has leveled off in recent years as Americans have

discovered equally rewarding-and sometimes safer- forms of exercise, such as walking and swimming, running

remains the most popular form of exercise.

     As the popularity of exercise continues to mount, so does scientific evidence of its health benefits. The key

to fitness is exercising the major muscle groups vigorously (强有力地) enough to approximately double the

heart rate and keep it doubled for 20 to 30 minutes at a time. Doing such physical exercises three times or more

a week will produce considerable improvements in physical health in about three months.

1. It can be learnt from the passage that the health benefits of exercise ____.

A. are to be further studied

B. are self-evident

C. are yet to be proved

D. are supported by scientific evidence

2. A growing interest in sports developed after ____.

A. an increasing number of races were held in American cities

B. research showed their health benefits

C. scientific evidence of health benefits was shown on TV ads

D. people got the message from magazine covers and postage stamps

3. Which of the following would be the best title for the passage?

A. Exercise-The Road to Health

B. Scientific Evidence of Health Benefits

C. Different Forms of Exercise

D. Running-A Popular Form of Sport

4. Which of the following is closest in meaning to the phrase "leveled off" in the paragraph 2?

A. Reached its lowest level in popularity.

B. Stopped being popular.

C. Stopped increasing in popularity.

D. Become very popular.