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 (過山車).
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 (肌陣攣的) 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 (收縮) 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.a(chǎn)bnormal D.useful
65.It can be inferred that myoclonic jerksD.
A.lead to muscle diseaseB.happen in a deep sleep
C.a(chǎn)re related to brain diseaseD.don't always wake people up.
分析 本文是科技短文.該文章主要介紹的科學(xué)研究證明:人在剛要睡著時,大腦會給身體發(fā)出一種信號--放松身體,準備入睡.這種信號在向身體傳遞時,身體肌肉會發(fā)出輕微的抖動,有時人就會醒來.剛要睡著卻突然驚醒,這是一種很正常的生理現(xiàn)象.
解答 CABD
62 C 細節(jié)理解題.由第三段"This is because your brain signals your body to relax to prepare for sleep."這是因為你的大腦要給你的身體發(fā)出指令:放松,準備睡覺,可知選C.
63 A 推理判斷題.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."你也許認為這會花上一段時間,但是你的大腦運轉(zhuǎn)那么快以致于它在你肌肉抽搐時同時編造了這樣的故事,所以答案選A.
64 B 細節(jié)理解題.A.worrying 令人焦慮的 B.usual 通常的 C.a(chǎn)bnormal 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!"因此你下次夢到墜落和大汗淋漓醒來,不要擔(dān)心.你的身體只是在告訴你的肌肉放松、休息,故選B.
65 D 推理判斷題.由文章倒數(shù)第二段"But many people don't realize their muscles are jerking during night sleep if it doesn't wake them up."但是很多人沒有意識到他如果沒有它把他叫醒,在夜晚睡眠時肌肉也會抽搐. 故選D.
點評 做閱讀理解時要快速的瀏覽全文,把握文章主旨大意,帶著問題回到原文,尋找細節(jié)或概括相應(yīng)的答案,最后要理清作者寫作思路.