【英语时差8,16】北极熊是怎样保持冷静的呢？

If you found yourself instantly transported to the freezing arctic, your first concern would be keeping warm. But what about the animals that make their homes on these vast fields of ice and snow? Do polar bears need to worry about freezing to death? Actually, a polar bear's biggest problem is keeping cool, not keeping warm. Thanks to its thick coat of fur, its tough hide, and a four inch layer of blubber, a polar bear is extremely well insulated. Indeed, if a resting polar bear is photographed with infra-red film–a kind of film which can measure the amount of heat escaping from a body–the polar bear won't even show up at all. That doesn't mean polar bears are as cold as the surrounding ice; their normal body temperature is about the same as ours. It simply means that polar bears retain their body heat very well. In fact, a polar bear can rest in a pit of icy snow, at temperatures as low as minus thirty-four degrees Fahrenheit¹, without needing to burn any extra fat for warmth! While this insulation² is great for keeping warm, it can lead to some serious overheating. As a result, polar bears don't like to run after their prey³. Chasing a seal at only four and a half miles an hour, a polar bear's temperature climbs to a feverish⁴ hundred degrees. It may have to lie on its back with its feet in the air to cool down. Polar bears prefer to hunt by waiting near a hole in the ice, and letting dinner come to them. It's the best way to conserve⁵ energy, and keep cool, in the Arctic north.

1 Fahrenheit   

n./adj.华氏温度；华氏温度计(的)

参考例句：

• He was asked for the boiling point of water in Fahrenheit.他被问到水的沸点是华氏多少度。
• The thermometer reads 80 degrees Fahrenheit.寒暑表指出华氏80度。

2 insulation   

n.隔离；绝缘；隔热

参考例句：

• Please examine the insulation of the electric wires in my house.请检查一下我屋子里电线的绝缘情况。
• It is always difficult to assure good insulation between the electric leads.要保证两个电触头之间有良好的绝缘总是很困难的。

3 prey   

n.被掠食者，牺牲者，掠食；v.捕食，掠夺，折磨

参考例句：

• Stronger animals prey on weaker ones.弱肉强食。
• The lion was hunting for its prey.狮子在寻找猎物。

4 feverish   

adj.发烧的，狂热的，兴奋的

参考例句：

• He is too feverish to rest.他兴奋得安静不下来。
• They worked with feverish haste to finish the job.为了完成此事他们以狂热的速度工作着。

5 conserve   

vt.保存，保护，节约，节省，守恒，不灭

参考例句：

• He writes on both sides of the sheet to conserve paper.他在纸张的两面都写字以节省用纸。
• Conserve your energy,you'll need it!保存你的精力，你会用得着的！