国家地理:Polar Bears 北极熊

Seventy-nine degrees north latitude¹ is near the top, at the cold edge of the world. In the winter, when temperatures plunge² below freezing, there is complete darkness at noon. During summer, the sun shines at midnight, there is no place to hide. Danger is everywhere. Life on Svalbard is intense, so was the hunger that burns inside this female polar bear. She eats seals that live on sea ice. But this spring she cannot find them, anywhere. The pack ice has not arrived. The bear needs food this summer, and she needs to store fat for the coming winter. If her icy world grows warmer, will she survive in the Arctic?

1 latitude   

n.纬度，行动或言论的自由(范围)，(pl.)地区

参考例句：

• The latitude of the island is 20 degrees south.该岛的纬度是南纬20度。
• The two cities are at approximately the same latitude.这两个城市差不多位于同一纬度上。

2 plunge   

v.跳入，(使)投入，(使)陷入；猛冲

参考例句：

• Test pool's water temperature before you plunge in.在你跳入之前你应该测试水温。
• That would plunge them in the broil of the two countries.那将会使他们陷入这两国的争斗之中。