Their biggest problem is the lack of water, 它们最大的困难莫过于缺水

12. Wild Bactrian camels,
    野双峰驼
13. one of the rarest mammals on the planet.
    一种地球上最稀有的哺乳动物
14. And perhaps the hardiest.
    可能也是最坚韧的动物
15. Their biggest problem is the lack of water,
    它们最大的困难莫过于缺水
16. particularly now, in winter,
    尤其是现在——冬天
17. when the little there is is locked up as ice.
    那里仅有的一点水也结成了冰
18. Surprisingly, snow here never melts.
    奇怪的是 这里的雪永远都不会融化

来自《行星地球 第一季 第五集 Planet Earth S01E05 沙漠》第 15 行