四六级考试

【单选题】An adult giraffe’s head is about six feet above its heart. This means that tocenough blood up to the brain the circulatory (68) 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 (69) high blood pressure, about (70) that of human beings.But an international team of biologists began to (71) about this. If giraffes havesuch high blood pressure, they should have a (72) problem with swelling in their legs and feet. Why don’t giraffes have swollen feet
Giraffes should have (73) problem, too.Every time they bend heads (74) to drink, the blood should (75) to their heads and have a hard time (76) back up (when the head is down) to the heart. How come giraffes don’t black out when they drink
The answer to the (77) feet problem, the researchers found, is that giraffes have (78) the researchers call a "natural anti-gravity suit". It 79 out that the skin and other (80) in their legs and feet are (81) stiffer and tougher than those of other (82) .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 (83) the giraffe bends down to drink The researchers found that the giraffe’s jugular vein, which (84) 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 (85) drinking water.By squeezing the valved jugular vein, they (86) blood moving back to the heart even while the animal is drinking.

A、other
B．some
C．others
D．another

网考网参考答案：D
网考网解析：
[解析] 词义辨析题。通读第三段可知，该段是在讲长颈鹿血压很高的话为什么喝水时不会晕倒这个问题，所以该空格所在句子意思是“长颈鹿还应该有另一个问题”，而不是“有其他问题”，所以D正确，排除A。 document.getElementById("warp").style.display="none"; document.getElementById("content").style.display="block"; 查看试题解析出处>>