And they have another reason to keep moving. 他们继续前行还有另一个原因
They need to descend as quickly as possible. 他们得尽快下山
And while they were half-asleep in the depths of winter, 他们在隆冬半梦半醒之际
And when spring comes, they emerge. 待春天来临 它们就出洞了
they are the most accomplished mountaineers. 让他们成为最高超的登山者
They may only be a fraction of the height of the Himalayas, 它们的海拔也许只是喜马拉雅山脉的零头
but they are still so dizzyingly steep 但却异常险峻
they have had to adapt both their body and their behaviour in order to survive. 为了生存 他们必须从体型和行为上 充分适应环境