Exercise is one of the few factors with a positive role in long-term maintenance (保持) of body weight.

Unfortunately, that message has not gotten through to the average American, who would rather try switching

to "light" beer and low-calorie bread than increase physical exertion (体能). The Centers for Disease Control,

for example, found that fewer than one-fourth of overweight adults who were trying to remove pounds said

they were combining exercise with their diet.

In rejecting exercise, some people may be discouraged too much by caloric-expenditure (卡路里的消耗)

charts; for example, one would have to actively walk three miles just to work off the 275 calories in one

delicious Danish pastry (小甜饼). Even exercise professionals admit half a point here. "Exercise by itself is a

very tough way to lose weight," says York Onnen, program director of the President' s Council on Physical

Fitness and Sports.

Still, exercisers supporting role in weight reduction is important. A study at the Boston University Medical

Center of overweight police officers and other public employees confirmed (证实) that those who dieted

without exercise regained almost all their old weight, while those who worked exercise into their daily routine

(常规)maintained their new weight.

If you have been sedentary (极少活动的) and decide to start walking one mile a day, the added exercise

could burn an extra 100 calories daily. In a year's time, supposing no increase in food intake, you could lose

ten pounds. By increasing the distance of your walks gradually and making other dietary adjustments, you may

lose even more weight.

1. What is said about the average American in the passage?

A. They usually ignore the effect of exercise on losing weight.

B. They prefer"light" beer and low calorie bread to other drinks and food.

C. They know the factors that play a positive role in keeping down body weight.

D. They tend to overemphasize the healthful effect of"light" beer.

2. Some people dislike exercise because ________.

A. they find it hard to exercise while on a diet

B. they don't think it possible to walk 3 miles every day

C. they think it is physically exhausting

D. they find consulting caloric-expenditure charts troublesome

3. What was confirmed by the Boston University Medical Center's study?

A. Weight reduction is impossible without exercise.

B. Even occasional exercise can help reduce weight.

C. Controlling one's calorie intake is more important than doing exercise.

D. One could lose ten pounds in a year's time if there's no increase in food intake.

4. What is the author's purpose in writing this article?

A. To stress the importance of maintaining proper weight.

B. To support the statement made by York Onex.

C. To show the most effective way to lose weight.

D. To introduce the study of the Boston University Medical Center.