托福阅读：Dehydration

水是生命之源，人类的生存不能离开水。在脱水的情况下人类能活多长时间呢?接下来的新托福考试阅读练习资料就来讨论这个话题。

If I were to stop drinking water right now, how long could I live?

There are different factors involved here. A human being isn’t an automobile which needs a certain amount of gas. There are conditions under which a person could die of dehydration within a single day, and other conditions whereby a person might live for over a week. It’s unlikely, though, anyone could go much beyond that.

Water comes into our systems not just from drinking but from eating as well. It goes out of us through urine, through sweat, and even through exhaling. Ever notice the fog you can make on a window by breathing on it? That’s water vapor leaving your body.

The biggest reason it’s bad to lose too much water is that the actual volume of your blood goes down. When blood volume goes down, blood pressure goes down. As blood pressure goes down, body heat goes up, because your blood helps regulate your core body temperature. Without enough blood, you can’t cool off. Pretty soon you overheat.

So various factors, from eating to circulatory health to the ambient temperature, play a part in how long you could go without water. Probably the biggest factor, though, is simply age: young people are much more likely to overheat faster than adults, which is why it’s especially important to keep an eye on the little ones on hot summer days.

以上就是这篇托福阅读材料，同学们可以积累其中的词汇及优美句式，找到托福阅读段的主题句，了解托福阅读的几个出题点。托福阅读训练是个长期的过程。大家如果每天做几篇阅读，坚持下来，一定会有不小的进步。预祝大家能有一个好的阅读成绩。