Exercise is one of the few factors with a positive role in long
term maintenance of body weight. Unfortunately, that message has
not gotten through to the average American, that would rather try __1__
switching to "light" beer and low-calorie bread than increase physical
exertion. The Centers for Disease Control, for example, found
that fewer than one-fourth of overweight adults were trying to shed __2__
pounds said they were combining exercise with their diet.
In rejecting exercise, some people may be discouraged too
much by calorie-expending charts; for example, one would have to __3__
briskly walk three miles just to work the 275 calories in one __4__
delicious Danish pastry. Even exercise professionals concede half a
point here. "Exercise in itself is a very tough way to lose weight," __5__
says York Onnen, the program director of the President's Council on __6__
Physical Fitness and Sports.
Therefore, exercise's supporting role in weight reduction is vital. __7__
A study at the Boston University Medical Center of overweight police
officers and other public employees confirmed that those who diet __8__
without exercise regained almost all their old weight, while those
who worked exercise into their daily routine maintained their new
weight.
If you decide to start walking one mile a day, the added exercise
could burn an extra 100 calories daily. In a year's time, assumed no __9__
increase in food takein, you could lose ten pounds. By increasing the __10__
distance of your walks gradually and making other dietary adjustments,
you may lose even more weight.

答案及解析：
1.that--who
that从句修饰的是the average American，而且它是一个非限定性定语从句，而that无法引导一个非限定性定语从句，所以应把that改为who。

2.adults^--who
found后接的从句中主要的动词应该是said，而不是try to shed pounds，所以应该在were前面加上who构成定语从句修饰overweight adults。

3.expending--expenditure
由于caloric是形容词，表示“属于或者关于卡的”，它后面不能接动词的-ing形式，而且expending和charts的关系也不成立，所以应该改为名词expenditure。

4.work^--off
work off有消耗之意，符合文义。

5.in--by(直接把in 去掉也可以吧？)
in itself 表示“本身，本质上”，而我们都知道锻炼是一减肥的好方法，只是不能仅靠锻炼，还需配之以适当的饮食控制，所以应该把in itself换成by itself，表示“单独”。

6.the(program)--/
在用作同位语表示独一无二的职位的名词之前，通常用零冠词。

7.Therefore--Still/Neverthless
根据上下文，这里要表达的关系是让步，不是因果。

8.diet--dieted
这里叙述的是过去的一项研究。

9.assumed--assuming
assume和you的关系应是主动的，所以应改为assuming。

10.takein--intake
take in 表示“摄入，吸收”，它的名词形式不是take in，而是 intake。