29号考试！求解答！rp感谢

liyi422

The chemical adenosine is released by brain cells when those cells are active.

Adenosine then binds to more and more sites on cells in certain areas of the

brain, as the total amount released gradually increases during wakefulness.

During sleep, the number of sites to which adenosine is bound decreases. Some

researchers have hypothesized that it is the cumulative binding of adenosine to a

large number of sites that causes the onset of sleep.



Which of the following, if true, provides the most support for the researchers’

hypothesis?

A.Even after long periods of sleep when adenosine is at its lowest concen-

tration in the brain, the number of brain cells bound with adenosine remains

very large.

B.Caffeine, which has the effect of making people remain wakeful, is known to

interfere with the binding of adenosine to sites on brain cells.

C.Besides binding to sites in the brain, adenosine is known to be involved in

biochemical reactions throughout the body.

D.Some areas of the brain that are relatively inactive nonetheless release

some adenosine.

E.Stress resulting from a dangerous situation can preserve wakefulness even

when brain levels of bound adenosine are high.

B

做了2次 答案都没选到B上去
请大侠帮忙解释

shencangbulu

第一遍看我也没能马上决定选B,但不选B其他的几个都更不靠谱,再看了一遍,B还是有点道理的,至少其他几个都是无关.

原文主要说的是大脑细胞在活跃的时候,比如白天,会释放一种化学物质A,当它越积越多之后,就会要减少,通过什么方法减少呢,就假设,比如它积累到一定的量,就会启动睡眠装置,所以人就会想睡觉,那这个时候A物质就能减少了.换句简单的话说,A物质在人睡眠的时候应该是减少的.

所以B是搭边的至少,已知咖啡因会让人保持清醒,会干扰A物质形成.换个角度想下,本来A增多增多,人是要睡眠趋势的,咖啡因的出现破坏了A的堆积起来,所以人就能保持清醒.

liyi422

谢谢！
基本看懂了，那个绕啊。。考试遇到铁定死菜。 呵呵。

再次感谢！