| 学习资料 —> 外语类 —> 四六级考试
 
决胜六级--阅读(3)
(发布时间:2007-3-12 19:08:00 来自:模考网)

1

Running a fever was once thought to be the prerogative of warmblooded creatures, whose internal temperatures are indpendent of the weather. But, as Matthew Kluger reported in “The Importance of Being Feverish” (January 1976), lizards can also develop fevers, even though there is no question that they are coldblooded. They raise their temperatures by moving into the sun or, in the case of Klugers experiments, under a sun lamp. And it seems to do them some good. Sick lizards kept in cages at feverish temperatures fare much better than their counterparts in normal and cool environments.

Now, fever has spread to invertebrates(无脊椎动物). Recent studies have shown that crayfish and scorpions can develop fevers. Crayfish injected with bacteria and scorpions injected with prostaglandins(前列腺素) swam and scuttled to hot areas. (Prostaglandins are hormones thought to be instrumental in the development of a fever.)

 Evidence is also mounting that moderate fevers have their benefits, which might explain why the fever process is so widespread. Leukocytes, white blood cells that are active in fighting bacterial infections, are more mobile at febrile temperatures. And fevers reduce the amount of iron available to bacteria. That reduction, combined with high temperatures, has been shown to inhibit bacterial growth.



1. Which of the following best states the main idea of the passage?

A. Coldblooded animals can develop fevers.

 [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [下一页]

 

收藏此页】【字体: 】【打印】【关闭