题目内容
10．Has this happened to you？You're about to drift off to sleep when suddenly you feel like you're falling or coming down on a roller coaster （过山车）．You then wake up to realize that you're safe in your bed．You may have been confused or frightened for a second or two and your heart may be beating faster．You may have also felt the muscles in your body jerk when this all happened．Did you ever wonder why？
This falling sensation，together with a body movement known as a"sleep start，"is what doctors and scientists call a myoclonic （肌阵挛的） jerk，and it usually happens right before going into deeper stages of sleep．Here's why doctors think the falling feeling and myoclonic jerks happen．When you fall asleep，normally your body temperature goes down and your heart starts to beat just a little slower．This is because your brain signals your body to relax to prepare for sleep．When your muscles are relaxed，you go into the very first stages of sleep，but you're not sleeping too deeply yet．
This brain activity may cause your larger muscles to contract （收缩） a little bit．In response，another part of your brain will make up a very quick mini-dream to go along with what is happening．You might think this would take a while，but your brain works so fast that it makes up the story almost at the same instant that your muscles jerk．
During this light sleep，you can be awakened easily．People who wake up during the light sleep believe they haven't fallen asleep yet．That's why you may think that your body jerked right before you were about to fall asleep．
Myoclonic jerks are a normal part of sleep．Most people have them at one time or another．But many people don't realize their muscles are jerking during night sleep if it doesn't wake them up．
So the next time you dream about falling and wake up in a sweat，don't worry!Your body is just telling your muscles to relax and get some rest!
62．People sometimes wake up during a light sleep becauseC．
A．they are disturbed by others
B．they are too tired to fall asleep
C．their bodies are preparing for sleep
D．they believe their lives are in danger
63．What does the underlined part"what is happening"in paragraph 4refer toA？
A．The body jerk．
B．The mini-dream．
C．The slow heartbeat．
D．The falling body temperature．
64．The author thinks myoclonic jerks during sleep areB．
A．worrying B．usual C．abnormal D．useful
65．It can be inferred that myoclonic jerksD．
A．lead to muscle diseaseB．happen in a deep sleep
C．are related to brain diseaseD．don't always wake people up．
分析 本文是科技短文．该文章主要介绍的科学研究证明：人在刚要睡着时，大脑会给身体发出一种信号--放松身体，准备入睡．这种信号在向身体传递时，身体肌肉会发出轻微的抖动，有时人就会醒来．刚要睡着却突然惊醒，这是一种很正常的生理现象．
解答 CABD
62 C 细节理解题．由第三段"This is because your brain signals your body to relax to prepare for sleep．"这是因为你的大脑要给你的身体发出指令：放松，准备睡觉，可知选C．
63 A 推理判断题．由第四段"You might think this would take a while，but your brain works so fast that it makes up the story almost at the same instant that your muscles jerk．"你也许认为这会花上一段时间，但是你的大脑运转那么快以致于它在你肌肉抽搐时同时编造了这样的故事，所以答案选A．
64 B 细节理解题．A．worrying 令人焦虑的 B．usual 通常的 C．abnormal 不正常的 D．useful 有用的，由文章最后一段"So the next time you dream about falling and wake up in a sweat，don't worry!Your body is just telling your muscles to relax and get some rest!"因此你下次梦到坠落和大汗淋漓醒来，不要担心．你的身体只是在告诉你的肌肉放松、休息，故选B．
65 D 推理判断题．由文章倒数第二段"But many people don't realize their muscles are jerking during night sleep if it doesn't wake them up．"但是很多人没有意识到他如果没有它把他叫醒，在夜晚睡眠时肌肉也会抽搐． 故选D．
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