18. Researchers have found that when very overweight people, who tend to have relatively low metabolic rates, lose weight primarily through dieting, their metabolisms generally remain unchanged. They will thus burn significantly fewer calories at the new weight than do people whose weight is normally at that level. Such newly thin persons will, therefore, ultimately regain weight until their body size again matches their metabolic rate.
The conclusion of the argument above depends on which of the following assumptions?
(A) Relatively few very overweight people who have dieted down to a new weight tend to continue to consume substantially fewer calories than do people whose normal weight is at that level.
(B) The metabolisms of people who are usually not overweight are much more able to vary than the metabolisms of people who have been very overweight.
(C) The amount of calories that a person usually burns in a day is determined more by the amount that is consumed that day than by the current weight of the individual.
(D) Researchers have not yet determined whether the metabolic rates of formerly very overweight individuals can be accelerated by means of chemical agents.
(E) Because of the constancy of their metabolic rates, people who are at their usual weight normally have as much difficulty gaining weight as they do losing it.

答案:A

虽然前面有过一个讨论，但mindfree大虾的答疑我还是没看明白~~

胖人的新陈代谢率慢，（什么叫做新陈代谢快呢？ 就是你吃的东西可以很

快的转化为热量消耗掉他，这种人就不会胖，但是胖的人就不会，这种人

很难burn Calories）,所以胖人通过节食减肥，摄入的能量少，这样即使

他消耗的少，也没有关系。

胖人节食--》 变瘦了，但是新陈代谢还是很慢——》因为新陈代谢慢，迟

早还是会胖的。

以上的这个关系，有一个漏洞是，变瘦的胖人 还是可以通过“继续”少摄

入能量来保持（摄入的少了，即使消耗的少也没有关系，还是可以继续保

持瘦的状态。）

所以A排除了上面这个漏洞，他说：几乎没有“过去胖现在瘦的人”会继续

consume substantially fewer calories

这是我的理解，不知道对不对~~~~~