Birds that are half

题文

Birds that are half-asleep—with one brain hemisphere (半球) 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 groups led rearchers to predict extra alertness in the end-of-the-row sleepers which tend to be attacked more easily. 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 napping at the end of the line depend on single-hemisphere sleep, rather than total relaxation, more often than inner ducks did. Turning 16 birds through the positions in a four-duck row, the rearchers found that compared with 12 percent for birds in internal spots, outer birds half-asleep during some 32 percent of napping time. “We believe this is the first evidence for an animal behaviorally controlling sleep and wakefulness at the same time in different regions of the brain,” the rearchers say. The results provide the best evidence for a long-standing assumption 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 en it in a pair of birds napping side-by-side in the zoo and in a single pet bird sleeping by a mirror. The mirror-side eye clod as if the reflection were a companion and the other eye stayed open. Uful as half-sleeping might be, it’s only been found in birds and such water animals as dolphins, whales, and als. 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.” He suppos that more examples may turn up when we take a clor look at other species.72. According to the passage, birds often half sleep becau ______. 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 companions73. What is implied about the example of a bird’s sleeping in front of a mirror? A. An imagined companion gives the bird a n of curity. B. Birds prefer to sleep in pairs for the sake of their curity. C. The phenomenon of birds napping in pairs is widespread.D. A single pet bird enjoys eing its own reflection in the mirror.74. While sleeping, some water animals tend to keep half awake in order to ______.A. alert themlves to the approaching enemy B. emerge from water now and then to breathe C. be nsitive to the ever-changing environment D. avoid being swept away by rapid currents75. By saying “just the tip of the iceberg”, Siegel suggests that ______. A. half-brain sleep has something to do with icy weather B. the mystery of half-brain sleep is clo to being solved C. most birds living in cold regions tend to be half sleepers D. half-brain sleep may exist among other species 题型：未知难度：其他题型

答案

72. A 73. A 74. B   75. D

解析

略

考点

据考高分专家说，试题“Birds that are half-.....”主要考查你对 [日常生活类阅读 ]考点的理解。 日常生活类阅读

日常生活类阅读的概念：

日常生活这一话题主要涉及人们衣食住行等方面的活动。这一话题的选材主要针对人们日常的工作，生活以及学习情况。做这一类题时，最主要的是要把握好人物的活动内容，时间和地点。

日常生活类阅读题答题技巧：

【题型说明】该类文章内容涉及到人们的言谈举止、生活习惯、饮食起居、服饰仪表、恋爱婚姻、消遣娱乐、节日起源、家庭生活等。文章篇幅短小，追根溯源，探索各项风俗的历史渊源，内容有趣。命题也以送分题为主，如事实细节题、语义转换题、词义猜测题和简单推理判断题等。虽然这类文章读起来感觉轻松，试题做起来比较顺手，但绝不能掉以轻心。因为稍不留神，就会丢分。 【备考提醒】为了保证较高准确率，建议同学们做好以下几点： 1、保持正常的考试心态。笔者在教学中发现，越是容易的试题，同学们越是容易失分。为什么呢？因为在这种情况下，同学们极易产生麻痹思想，认为题目好做，就不引起高度重视，于是思维不发散、不周密。而命题人就是利用同学们的这一弱点，设计陷阱题。所以，无论试题难易与否，我们都要保持正常的考试心态。试题容易，不欣喜；试题难，不悲观。 2、根据前面讲到的方法，认认真真、细细心心做好事实细节题。 3、做好语义转换题。这类题是根据英语中一词多义和某些词语在文中能表达一定的修辞意义的原则而设计的。要求同学们解释某生词的含义，确定多义词或短语在文中的意思，确认文中的某个代词所指代的对象，或者对英语中特有的表达、格言、谚语进行解释。这种题要求同学们一定要根据上下文猜测词义或理解句子，切不可望文生义。 4、做好简单推理判断题。简单推理判断题要以表面文字为前提，以具体事实为依据进行推理，做出判断。这种推理方式比较直接，只要弄清事实，即可结合常识推断出合理的结论。