Surprisingly only two percent of the sunlight filters down to the forest floor. 只有百分之二的阳光能够照射到雨林的地表上
Their parents lead them down to the safety of the water as soon as they're strong enough to make the journey. 它们强壮得可以旅行时, 父母马上就带着它们来到更为安全的水域
Exhausted and starving, they touch down inside the Arctic Circle, 虽然早己精疲力竭 饥肠辘辘 但它们终于返回了北极圈
They trim the grass down to its roots, leaving little in their wake, 这些角马拼命地吃草 把草根上面的草茎部分全部吃掉
As winter advances, frequent blizzards drive the temperature down. 随着隆冬的逼近,暴风雪越来越频繁 温度越来越低
and head down to the bottom of the gorge. 奔向峡谷底部
running out of air down here would be fatal. 在这里 耗尽氧气将是致命的
Collectively they've worn down mountains 它们共同抚平高山
In cooler climes, mud, laid down in estuaries, 在较冷的地区 沉积在入海口的泥沙
They can stay down for more than 30 seconds 它们能在水下呆30多秒