There is no living creature that does not need sleep or complete rest every day. If you want to know why, just try (41) without sleep for a long period of time! You (42) discover that your mind and body would become (43) tired to work properly. You would become irritable and find it hard to think clearly or (44) on your work. So sleep is quite (45) the time when the cells of your body (46) from the work of the day and (47) supplies of energy for the next (48) of activity.
One of the things we all know about sleep is that we are (49) in sleep. We do not know what is (50) on around us. But that does not mean the body stops (51) activity. The vital organs continue to work during sleep, but most of the body functions are (52) down.
For example, our breathing becomes slower and deeper. The heart beats (53) slowly, and the blood pressure is lower. Our arms and legs become limp(软弱的), and muscles that control our posture(姿势) are (54) . It would be impossible for our body to relax to such an (55) if we were awake. So sleep does for us (56) the most quiet rest cannot do.
Your body temperature becomes lower when you are asleep, (57) is the reason people go to sleep under some kind of (58) . And even though you are unconscious, ninny of your reflexes (反射作用) still work. (59) , if some one tickles your foot, you will pull it away in your sleep, or even (60) a fly from your forehead. You do these things without knowing it.

【正确答案】 B

【答案解析】will表示“将要发生的事情或状态”；A项表示“预先的计划”；C项表示“很近的将来，马上要做的事情”；D项shall的主语应为第一人称。本句意思是“你将会发现自己的大脑和身体太疲惫而不能正常工作”。

【正确答案】 D

【答案解析】concentrate... on... 为固定词组，意为“专心致志于某事”。hold on意思是“维持，等待”。此题应根据意思选择。此句意为“你会变得急躁，并且发现清晰思维或者专心工作是很难的”。

【正确答案】 A

【答案解析】此处需填入一个副词来修饰该句。B，C项为形容词，应排除。根据句意应选择 A项simply“简单地”。该句意思是“简单地说，睡眠就是这样一段时间，你体内的细胞在一天的工作后得到恢复，并在此期间为下一个阶段的活动储备能量”。