2. 外语
  3. An adult giraffe’s head is about six feet above its heart. This means that to 【C1】______ enough blood up to the brain the circul

An adult giraffe’s head is about six feet above its heart. This means that to 【C1】______ enough blood up to the brain the circul

admin2012-12-13  68
问题 An adult giraffe’s head is about six feet above its heart. This means that to 【C1】______ enough blood up to the brain the circulatory 【C2】______ must be strong enough to keep the blood at very high pressure.
Biologists have known for some time that giraffes solve this problem by having 【C3】______ high blood pressure, about 【C4】______ that of human beings. But an international team of biologists began to 【C5】______ about this. If giraffes have such high blood pressure, they should have a 【C6】______ problem with swelling in their legs and feet. Why don’t giraffes have swollen feet?
    Giraffes should have 【C7】______ problem, too. Every time they bend heads 【C8】______ to drink, the blood should 【C9】______ to their heads and have a hard time 【C10】______ back up (when the head is down) to the heart. How come giraffes don’t black out when they drink?
    The answer to the 【C11】______ feet problem, the researchers found, is that giraffes have 【C12】______ the researchers call a "natural anti-gravity suit". It 【C13】______ out that the skin and other 【C14】______ in their legs and feet are 【C15】______ stiffer and tougher than those of other 【C16】______ . As a result, the blood vessels in the leg cannot swell.
    Therefore, the blood has nowhere to go but back to the heart. What about blood rushing to the head 【C17】______ the giraffe bends down to drink? The researchers found that the giraffe’s jugular vein, which 【C18】______ blood from the head back to the heart, has lots of one-way valves in it. In the giraffe’s neck, there are lots of muscles that flex and relax repeatedly as the animal moves its head and sucks 【C19】______ drinking water. By squeezing the valved jugular vein, they 【C20】______ blood moving back to the heart even while the animal is drinking.
【C1】
选项 A、bring
B、produce
C、transfer
D、pump
答案D
解析 词义辨析题，文章第一句就指出，成年长颈鹿的脑袋在心脏以上6英尺高的地方，空格所在句子意思是：这意味着，要______足够的血液到大脑，循环______必须足够强壮才能保持血液有很强的压力，pump除了表示“用泵抽”之意，还可以表示“(用泵拉取)注入”，符合句意，所以D正确
转载请注明原文地址:https://www.kaotiyun.com/show/0Cw7777K
0

大学英语四级

相关试题推荐
随机试题
最新回复(0)