单选题 One fact was clearly demonstrated by the early sleep researchers: one part of the night is not just like another. As scientists began to compare the records of volunteers during the 1950s, they observed that human sleep follows a rhythmic schedule. They noted that not only was this schedule much the same in healthy persons of the same age with similar habits but, from night to night, each individual had an EEG record almost as consistent as a signature.
Sleep and wakefulness, once considered to be the light and dark of consciousness, no longer seem to differ so sharply. To sleep does not mean to drown in an ocean of darkness. Actually, sleep is not a unitary state; it involves many shades or degree of detachment from the surrounding world. While sleep may feel like a blanket of darkness punctuated by dreams—a time when the mind is asleep—nothing could be less true. All night long a person drifts down and up through different levels of consciousness, as if on waves. With laboratory methods, researchers have been able to chart the typical stages of the journey into sleep.
The journey starts while the subject is still awake but beginning to relax. His brain waves, which have been low, rapid, and irregular, begin to show a new pattern. This new pattern, which is known as alpha rhythm, is an even electrical pulsation of about nine to 12 cycles per second. Most people do not know what the alpha state feels like, but during the last few years researchers have been able to teach subjects how to recognize and control their alpha rhythm.
When their EEG shows an alpha rhythm, the subjects are notified, either by a sound or by the appearance of a color on a screen. Because the alpha state tends to be pleasant and relaxed, the ability to sustain it can help tense people ease their passage into sleep. A moment of tension, a loud noise, an attempt to solve a problem, however, and the alpha rhythm may vanish.
As the subject passes through the gates of the unconsciousness, his alpha waves grow smaller, and his eyes roll very slowly. For a moment, he may wake up during this early part of the descent, alerted by a sudden spasm that causes his body to jerk. Like the brain waves, this spasm is a sign of neural changes within. Known as the myoclonic jerk, it is caused by a brief burst of activity in the brain. Although it is related to epileptic seizures, the myoclonic jerk is normal in all human sleep. It is gone in a fraction of a second, after which descent continues. The subject has not felt the peculiar transformation, but now he is said to be truly asleep.

单选题 This passage states that a person is really asleep only

A. after dreaming has passed.
B. when his EEG reveals no alpha rhythm.
C. when his EEG begins to show an alpha rhythm.
D. after the completion of his alpha rhythm decline.

【正确答案】 D

【答案解析】[解析] 本题考查推理判断。该题询问人真正进入睡眠状态是在什么时候。文章先是对人的睡眠进行浅析，而后对进入自然睡眠的过程进行如实描述，而真正进入睡眠状态是该过程所要达到的一个最终状态，所以答案应在文章末尾。文章的第三段开始讲述人在处于彻底放松，将要入睡时，他的脑电波就会出现“alpha rhythm”，而且随着人的意识逐渐模糊，“alpha rhythm”的强度会不断削弱，直到文章最后一段的最后两行所描述的“It is gone in a fraction of a second，after which descent continues．The subject has not felt the peculiar transformation，but now he is said to be truly asleep．”在人进入熟睡的过程中会伴有瞬间的抽动，这之后“alpha rhythm”继续减弱直到完全消失，这时人才真正进入到无意识的熟睡状态。句中“descent continues”是指“alpha rhythm's descent continues”。因此人进入真正的睡眠状态是在“alpha rhythm”完全消失以后。

单选题 According to the author, the alpha state has been shown to be

A. immeasurable.
B. erratic in its rhythm.
C. a brief burst of activity in the brain.
D. controllable.

【正确答案】 D

【答案解析】[解析] 本题考查细节理解。作者在第三段最后指出“during the last few years researchers have been able to teach subjects how to recognize and control their alpha rhythm．”研究人员已经能够教人们如何辨认并控制他们的“alpha rhythm”了，所以“alpha rhythm”是可控制的。选项 [A]与文章内容不符，第四段第一句话表明“alpha rhythm”可以用声音或色彩来记录下来，因此不是“unmeasurable”；选项[B]认为“alpha rhythm”是“erratic”(不稳定的)，而文章第三段指出“alpha rhythm”是“an even electrical pulsation of about nine to 12 cycles per second”平缓的有节奏的电波震动，每秒钟9到12次。由此可见，“alpha rhythm”具有很强的稳定性，所以应排除选项[B]；选项[C] a brief burst of activity in the brain在最后一段中是引起“myoclonic jerk”的原因，而且“It is gone in a fraction of a second”，而不是像“alpha rhythm”一样一直存在于人从放松到睡眠的过程中，所以不能被认为是“alpha rhythm”的表现形式。

单选题 Sleep is described as

A. a gradual parting from the real world.
B. undisturbed by tension or problems.
C. drowning in an ocean of darkness.
D. dependent only upon individual age and health.

【正确答案】 A

【答案解析】[解析] 本题考查细节理解。第二段指出“Actually，sleep is not a unitary state；it involves many shades or degree of detachment from the surrounding world．(睡眠不是一个单一的状态，而包含超脱周围现实世界的色彩浓度或程度。)”选项[A]的内容正好与原文意思相符。而选项[C]的内容与第二段第二句话“To sleep does not mean to drown in an ocean of darkness．”意思相反，应排除；第四段第三句话表明人的睡眠状况与人的精神状况有关，并未提到年龄与健康对睡眠的影响，所以选项[D]也应排除；选项[B]是讲“睡眠不受紧张与各种问题的影响”，这与原文“A moment of tension，a loud noise，an attempt to solve a problem，however，and the alpha rhythm may vanish．”所表达的意思完全相反，应排除。

单选题 All of the following were suggested as being used by sleep researchers except

A. projection.
B. hypnosis.
C. charts.
D. recorders.

【正确答案】 B

【答案解析】[解析] 本题考查细节理解。文章中“When their EEG shows an alpha rhythm，the subjects are notified，either by a sound or by the appearance of a color on a screen．”表明研究人员在进行研究时采取了用EEG作图的方法，即“charts”，而后将它用色彩来表达并投放在屏幕上，即“projection”投影；或者是将它录制下来用声音来表示，即“recorders”。所以研究人员是采用“charts”“projection”“recorder”三种方法进行研究的而不是hypnosis“催眠”。

单选题 The use of the term "subjects" in the selection refers to

A. waves.
B. dreams.
C. volunteers.
D. measurements.

【正确答案】 C

【答案解析】[解析] 本题考查词义辨认。本文在第一段提㈩研究人员对一些志愿者“volunteers”进行睡眠研究，并将其记录进行对比得出结论。而文章在后边的内容中就对该研究进行了详述，如最后一段话的第一句“As the subject passes through the gates of the unconscious，his alpha waves grow smaller，and his eyes roll very slowly．”当实验对象进入意识模糊的状态时，他的“alpha waves”会减慢，而且眼睛的转动速度也会很慢。这句话的主语与后边的“his”是指同一事物，即研究人员的实验对象，也就是第一段第二句话所提到的在50年代参与实验的“volunteers”。所以文章在之后的描述中均用“subject”替代了“volunteer”。