36.根据短文内容，从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。

　　It’s such a common event that you probably never asked yourselfwhy you sleep. ___36___. In fact, for sleep researchers, it’s one of thebiggest unanswered questions in the field.

　　Stop and think about it for a second. Why should we sleep? ___37___. But we sleep every night, even when we have had plenty of rest. There are, nodoubt, several different answers to this question, but let’s just consider onegeneral purpose of sleep: ___38___. Human beings are creatures that arenormally active during daylight hours, when our senses functions mosteffectively. ___39___. We can’t see objects well, our color vision isentirely lost, and we don’t have the smelling or hearing sharpness of otheranimals. So it actually does make sense to have us stay where we are during thedangerous period when night-waking animals are walking here and there. And onesure way to make sure we don’t fall down everywhere and get lost or eaten is tohave us not move for seven or eight hours, rising again only when the light isback and our survival chances are better.

 　　It’s not the only reason wesleep. ___40___. Perhaps even the most important one.

A. Is it because we get tired?

B. Should that put human beings in a terrible situation?

C. But from a scientific point of view, this is far from anordinary matter.

D. But in terms of evolution, it may have been one of the firstreasons.

E.Furthermore, if you were designing an animal, would you have it come into longperiods of unconsciousness every twenty-four hours?

F. Sleep as a survival approach.

G. At night, humans do rather poorly.