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Birds that are literally half-asleep—with one brain hemisphere alert and the other sleeping—control which side of the brain remains awake, according to a new study of sleeping ducks.
Earlier studies have documented half-brain sleep in a wide range of birds. The brain hemispheres take turns sinking into the sleep stage characterized by slow brain waves. The eye controlled by the sleeping hemisphere keeps shut, while the wakeful hemisphere’s eye stays open and alert. Birds also can sleep with both hemispheres resting at once.
Decades of studies of bird flocks led researchers to predict extra alertness in the more vulnerable, end-of-the-row sleepers. Sure enough, the end birds tended to watch carefully on the side away from their companions. Ducks in the inner spots showed no preference for gaze direction.
Also, birds dozing (打盹)at the end of the line resorted to single-hemisphere sleep, rather than total relaxation, more often than inner ducks did. Rotating 16 birds through the positions in a four-duck row, the researchers found outer birds half-asleep during some 32 percent of dozing time versus about 12 percent for birds in internal spots.
“We believe this is the first evidence for an animal behaviorally controlling sleep and wakefulness simultaneously in different regions of the brain,” the researchers say.
The results provide the best evidence for a long-standing supposition that single-hemisphere sleep evolved as creatures scanned for enemies. The preference for opening an eye on the lookout side could be widespread, he predicts. He’s seen it in a pair of birds dozing side-by-side in the zoo and in a single pet bird sleeping by a mirror. The mirror-side eye closed as if the reflection were a companion and the other eye stayed open.
Useful as half-sleeping might be, it’s only been found in birds and such water mammals (哺乳动物）as dolphins, whales, and seals. Perhaps keeping one side of the brain awake allows a sleeping animal to surface occasionally to avoid drowning.
Studies of birds may offer unique insights into sleep. Jerome M. Siegel of the UCLA says he wonders if birds, half-brain sleep “is just the tip of the iceberg(冰山).” He speculates that more examples may turn up when we take a closer look at other species.
1
A new study on birds’ sleep has revealed that _____.
A.
half-brain sleep is found in a wide variety of birds
B.
half-brain sleep is characterized by slow brain waves
C.
birds can control their half-brain sleep consciously
D.
birds seldom sleep with the whole of their brain at rest
本题答案：
A
B
C
D
参考答案：
C
系统解析：
第1段提到“根据对睡鸭的一项新研究，那些真正进行半脑睡眠的鸟类——它们半个大脑警醒，半个大脑沉睡——控制着让哪一半大脑保持清醒”，也就是说能自觉地控制大脑的状况，C正确。A和B是早期研究的结果；D与文章的意思不符。
2
According to the passage, birds often half sleep because ______.
A.
they have to watch out for possible attacks
B.
their brain hemispheres take turns to rest
C.
the two halves of their brain are differently structured
D.
they have to constantly keep an eye on their companions
本题答案：
A
B
C
D
参考答案：
A
系统解析：
第6段首句提到“新的研究成果为长期以来的一种设想提供了最好的证据，即半脑睡眠机制是动物为防范敌人进化而来的”，A与文章观点一致；B只是讲述了半脑睡眠是怎么回事，并没有告知原因；C文中没有提 及；D与文中内容不符。
3
The example of a bird sleeping in front of a mirror indicates that _____.
A.
the phenomenon of birds dozing in pairs is widespread
B.
birds prefer to sleep in pairs for the sake of security
C.
even an imagined companion gives the bird a sense of security
D.
a single pet bird enjoys seeing its own reflection in the mirror
本题答案：
A
B
C
D
参考答案：
C
系统解析：
第6段最后两句提到“研究者看见一只鸟儿靠着镜子睡觉。那只鸟对着镜子的那只眼睛是闭着的，仿佛镜中的影像是它的同伴，而它的另外一只眼则是睁开的”，C与此一致。A和B中的in pairs是对原文的误读；鸟儿喜欢结群（而不一定是成双成对）睡眠，文章前几段对此有说明。D中的enjoy属于无中生有。
4
While sleeping, some water mammals tend to keep half awake in order to_____.
A.
alert themselves to the approaching enemy
B.
emerge from water now and then to breathe
C.
be sensitive to the ever-changing environment
D.
avoid being swept away by rapid currents
本题答案：
A
B
C
D
参考答案：
B
系统解析：
第7段末句提到“也许一边大脑保持清醒是为了让睡眠中的动物不时浮出水面以免被淹死”，B与文中所提及的观点一致。
5
By “just the tip of the iceberg" (Line 2, Para. 8), Siegel suggests that ______.
A.
half-brain sleep has something to do with icy weather
B.
the mystery of half-brain sleep is close to being solved
C.
most birds living in cold regions tend to be half sleepers
D.
half-brain sleep is a phenomenon that could exist among other species
本题答案：
A
B
C
D
参考答案：
D
系统解析：
最后一段提到“Siegel说他想知道鸟类的半脑睡眠机制是否‘只是冰山浮出水面的那一角’，并推测当我们进一步研究其他物种时可能还会发现更多的例子”，D与文中所述相符。A文中没有提及；B、C与文意不符。
The destruction of our natural resources and contamination of our food supply continue to occur, largely because of the extreme difficulty in affixing (把……固定)legal responsibility on those who continue to treat our environment with reckless abandon. Attempts to prevent pollution by legislation, economic incentives and friendly persuasion have been met by lawsuits, personal and industrial denial and long delays—not only in accepting responsibility, but more importantly, in doing something about it.
It seems that only when government decides it can afford tax incentives or production sacrifices is there any initiative for change. Where is industry’s and our recognition that protecting mankind’s great treasure is the single most important responsibility? If ever there will be time for environmental health professionals to come to the frontlines and provide leadership to solve environmental problems, that time is now.
We are being asked, and, in fact, the public is demanding that we take positive action. It is our responsibility as professionals in environmental health to make the difference. Yes, the ecologists, the environmental activists and the conservationists serve to communicate, stimulate thinking and promote behavioral change. However, it is those of us who are paid to make the decisions to develop, improve and enforce environmental standards, I submit, who must lead the charge.
We must recognize that environmental health issues do not stop at city limits, county lines, state or even federal boundaries. We can no longer afford to be tunnel-visioned in our approach. We must visualize issues from every perspective to make the objective decisions. We must express our views clearly to prevent media distortion and public confusion.
I believe we have a three-part mission for the present First, we must continue to press for improvements in the quality of life that people can make for themselves. Second, we must investigate and understand the link between environment and health. Third, we must be able to communicate technical information in a form that citizens can understand. If we can accomplish these three goals in this decade, maybe we can finally stop environmental degradation, and not merely hold it back. We will then be able to spend pollution dollars truly on prevention rather than on bandages.
6
We can infer from the first two paragraphs that the industrialists disregard environmental protection chiefly because ______.
A.
they are unaware of the consequences of what they are doing
B.
they are reluctant to sacrifice their own economic interests
C.
time has not yet come for them to put due emphasis on it
D.
it is difficult for them to take effective measures
本题答案：
A
B
C
D
参考答案：
B
系统解析：
根据第1段末句“个人和企业拒绝和长期拖延在防治污染方面承担责任或采取行动”和第2段首句“似乎只有政府下决心提供税收优惠政策或牺牲生产，情况才会开始有所改变”，可知企业忽视环境保护主要出于经济效益的考虑，B正确。A、C与文中所陈述之意相悖；D文中没有提及。
7
The main task now facing ecologists, environmental activists and conservationists is ______.
A.
to prevent pollution by legislation, economic incentives and persuasion
B.
to arouse public awareness of the importance of environmental protection
C.
to take radical measures to control environmental pollution
D.
to improve the quality of life by enforcing environmental standards
本题答案：
A
B
C
D
参考答案：
B
系统解析：
第3段第3句提到：生态学者、环境保护积极分子和环境保护论者应积极与人们交流思想，激起人们思考环境问题，并促进人们的行为发生变化，由此可知B正确。A、C都不是他们的任务；D文中没有提及。
8
The word “tunnel-visioned” (Line 2，Para. 4)most probably means “_____”.
A.
narrow-minded
B.
blind to the facts
C.
short-sighted
D.
able to see only one aspect
本题答案：
A
B
C
D
参考答案：
D
系统解析：
考查的生词是tunnel“隧道”和vision“洞察力，视力”的合成词。结合文章第4段：在方法上，我们再也不能tunnel-visioned，我们必须从各个方面对待问题，并做出客观的决定。由此可知tunnel-visioned是“从各个方面看问题的”反义词，再结合字面意思，可猜测该词意为“片面地看问题”，D正确。
9
According to the author, what should play the leading role in the solution of environmental problems?
A.
Legislation and government intervention.
B.
The industry’s understanding and support.
C.
The efforts of environmental health professionals.
D.
The cooperation of ecologists, environmental activists and conservationists.
本题答案：
A
B
C
D
参考答案：
C
系统解析：
第1段第3句提到：环保专业人员走在前头，在解决环境问题中起领导作用的时机已经到来。第3段最后一句又指出：我们这些拿薪水为环保工作的发展、提高出谋划策并执行环境标准的人必须承担起领头的责任。因此，C正确。其他三项均不是起关键作用的因素。
10
According to the last paragraph, we learn that ______.
A.
efforts should be exerted on pollution prevention instead of on remedial measures
B.
more money should be spent in order to stop pollution
C.
ordinary citizens have no access to technical information on pollution
D.
environmental degradation will be stopped by the end of this decade
本题答案：
A
B
C
D
参考答案：
A
系统解析：
文章最后一句提到：如果这10年我们能实现这三个目标，也许最终我们能阻止而不是暂时抑制环境的恶化。那么我们也就不用采取补救措施，而且能将治理污染的费用真正用于保护环境。bandage原义为“绷带”，这里取比喻义，意为“治疗，补救”。A正确；B文中没有提及；C、D与文意相悖。
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