Question

阅读理解 　　Below is a selection from a popular science book． 　　If blood is red, why are veins(静脉)blue? 　　Actually, veins are not blue at all．They are more of a clear, yellowish colour．Although blood looks red when it's outside the body, when it's sitting in a vein near the surface of the skin, it's more of a dark reddish purple colour．At the right depth, these blood-filled veins reflect less red light than the surrounding skin, making them look blue by comparison． 　　Which works harder, your heart or your brain? 　　That kind of depends on whether you are busy thinking or busy exercising．Your heart works up to three times harder during exercise, and shifts enough blood over a lifetime to fill a supertanker．But, in the long run, your brain probably tips it, because even when you're sitting still your brain is using twice as much energy as your heart, and it takes four to five tunes as much blood to feed it． 　　Why do teeth fall out, and why don't they grow back in grown-ups? 　　Baby(or "milk")teeth do not last long; they fall out to make room for bigger, stronger adult teeth later on．Adult teeth fall out when they become damaged, decayed and infected by bacteria．Once this second set of teeth has grown in, you're done．When they're gone, they're gone．This is because nature figures you're set for life, and what controls regrowth of your teeth switches off． 　　Do old people shrink as they age? 　　Yes and do．Many people do get shorter as they age．But, when they do, it isn't because they're shrinking all over．They simply lose height as their spine(脊柱)becomes shorter and more curved due to disuse and the effects, of gravity(重力)．Many(but not all)men and women do lose height as they get older．Men lose an average of 3-4 cm in height as they age, while women may lose 5 cm or more．If you live to be 200 years old, would you keep shrinking till you were, like 60 cm tall, like a little boy again? No, because old people don't really shrink! It is not that they are growing backwards－their legs, arms and backbones getting shorter．When they do get shorter, it's because the spine has shortened a little．Or, more often, become more bait and curved． 　　Why does spinning make you dizzy(眩晕的)? 　　Because your brain gets confused between what you're seeing and what you're feeling．The brain senses that you're spinning using special gravity-and-motion-sensing organs in your inner ear, which work together with your eyes to keep your vision and balance stable．But when you suddenly stop spinning the system goes out of control, and your brain thinks you're moving while you're Dot! 　　Where do feelings and emotions come from? 　　Mostly from an ancient part of the brain called the limbic system．All mammals have this brain area－from mice to dogs, cats, and humans．So all mammals feel basic emotions like fear, pain and pleasure．But since human feelings also involve other, newer bits of the brain, we feel more complex emotions than any other animal on the planet． 　　If exercise wears you out, how can it be good for you? 　　Because our bodies adapt to everything we do to them．And as far as your body is concerned, it's "use it, or lost it”! It's not that exercise makes you healthy; it's more that a lack of exercise leaves your body weak and easily affected by disease． (1) What is the colour of blood in a vein near the surface of the skin? [　　] A． Blue． B． Light yellow． C． Red． D． Dark reddish purple． (2) Why do some old people look a little shrunken as they age? [　　] A． Because their spine is in active use． B． Because they are more easily affected by gravity． C． Because they keep growing backwards． D． Because their spine becomes more bent． (3) Which of the following statements about our brain is true? [　　] A． In the long run, our brain probably works harder than our heart． B． When our brain senses the spinning, we will fell dizzy． C． The brains of the other mammals are as complex as those of humans． D． Our feelings and emotions come from the most developed area in our brain． (4) What is the main purpose of the selection? [　　] A． To give advice on how to stay healthy． B． To provide information about our body． C． To challenge new findings in medical research． D． To report the latest discoveries in medical science．

Answer 1

答案：1．D;2．D;3．A;4．B;
解析：

(1)	细节理解题。难度：容易。从第三段第二行when it\s sitting in the vein near the surface of the shin, it\s more of a dark reddish purple colour．可知选项D正确。
(2)	细节理解题。难度：容易。从第九段的when they do get shorter, it's not because the spine has shortened a little．Or more often, become more bent and curved．可知老年人变矮不是因为他们的脊柱变短，更多的原因是因为他们的脊柱变弯曲。所以D选项正确。A选项的内容文中没有提及；B选项不符合文中的内容 They simply lose height as their spine(脊柱)becomes shorter and more curved due to disuse and the effects of gravity(重力)；C 选项的内容与文中的描述相反。
(3)	细节理解题。难度：中等。从文中but in the long run,, your brain probably tips it, because even when you're sitting still your brain is using twice as much as energy as your heart，可知选项A正确。 　　第十一段的第一句就说明了人感到眩晕的原因是因为大脑分不清我们所看到的和所想的东西，排除B；从第十三段的描述but since human feelings also involve other, newer bits of the brain, we feel more complex emotions than any other animals on the planet．可知C选项错误；从第十二段的副标题和十三段的第一句mostly from an ancient part of the brain called the limbic system可知D选项错误。
(4)	主旨大意题。难度：容易。从文章的副标题可知这篇文章解释了七个我们既熟悉又陌生的有关人体知识的问题，所以选项B正确，A、C和D选项在文中均没有提及。