Both poles of our planet are covered with ice. 地球的两极都被冰覆盖着

1. Both poles of our planet are covered with ice.
   地球的两极都被冰覆盖着
2. They're the largest and most demanding wildernesses of all.
   是最大、最荒凉的无人区
3. Nowhere else on Earth is seasonal change so extreme.
   两极地区的季节变化非常极端
4. It causes the ice to advance and retreat every year.
   使得冰盖面积每年都在扩大和缩小

来自《行星地球 第一季 第六集 Planet Earth S01E06 冰雪世界》第 1 行