听力原文

It's the beginning of winter, high up on the Tibetan plateau.
初冬，高高的青藏高原之上，
The temperature will soon drop to minus 40 Celsius.
气温会骤降到零下40摄氏度。
Out here, life is reduced to a single imperative - survival. For the argali, the world's largest sheep, it means searching for a few tufts of grass.
在这里生命中只剩下唯一的念头——求存。对于这只盘羊——世界上最大的羊而言，这就意味着寻找几簇草丛从山顶到更低一些的地方。
Descending from the hilltops to lower altitudes, the argali band together for safety.
盘羊为了安全而团结在一起，如果顺利的话
Hopefully, down here, they'll be able to find enough food to last them through the rest of the winter.
在这里能找到足够的食物，以帮助它们熬过残冬。
Although this winter landscape looks barren and forbidding, Tibet's remote grasslands support a surprising variety of creatures.
尽管冬的大地是如此的贫瘠与荒凉，西藏偏远的草地却养活着种类多的令人吃惊的生物
Though at this time of year, they can be hard to track down.
尽管每年的这个时候难以寻觅它们的踪迹。

重点讲解

重点讲解：
1. be able to do sth.
能做到某事；
eg. You'll be able to read in peace.
你就能安心地读书了。
eg. It would be nice to be able to afford to retire earlier.
无后顾之忧而能提早退休当是件幸事。
2. a variety of
各式各样；多种多样；
eg. The island offers such a wide variety of scenery and wildlife.
这个岛屿拥有丰富多样的景致及种类繁多的野生动植物。
eg. People change their mind for a variety of reasons.
人们会由于种种原因改变主意。
3. track down
追踪到；追查到；搜寻到；
eg. She had spent years trying to track down her parents.
她已经花了好多年时间试图追寻父母的下落。
eg. I don't know where that old story came from, I've never been able to track it down.
我不知道这则旧传闻的出处，我从来没能考证出结果。