One of the limiting factors in human physical performance is the amount of oxygen that is absorbed by the muscles from the bloodstream. Accordingly, entrepreneurs have begun selling at gymnasiums and health clubs bottles of drinking water, labeled “SuperOXY,” that has extra oxygen dissolved in the water. Such water would be useless in improving physical performance, however, since the only way to get oxygen into the bloodstream so that it can be absorbed bye the muscles is through the lungs.

Which of the following, if true, would serve the same function in the argument as the statement in boldface?

A. the water lost in exercising can be replaced with ordinary tap water

B. the amount of oxygen in the blood of people who are exercising is already more than the muscle can absorb

C. world-class athletes turn in record performance without such water

D. frequent physical exercise increases the body’s ability to take in and use oxygen

E. lack of oxygen is not the only factor limiting human physical performance

答案b，这道题还挺新鲜，思路理不清

Argument的conclusion是Such water would be useless in improving physical performance。boldface句子起到了支持的作用。答案中能对conclusion起到支持作用的就是b。

答案是B.

本题从形式上，我还真是第一次见到（见识短啊！）。

仔细一看，这个题就相当于填空题，你可以认为boldface部分是空白好了。

只需要找理由说明，为什么Such water would be useless in improving physical performance。

选项B.说明，肌肉已经无法再吸收更多的氧了。所以，Such water would be useless in improving physical performance。