听力文本

Giant salamanders, the world's largest amphibian, almost two metres long.
大鲵——世界上最大的两栖动物，几乎能长到2米长
They're the only large predator in these icy waters. They begin their hunt at night.
它们是这些冰水中唯一的大型掠食动物。夜幕降临，它们开始捕猎
These salamanders have an exceptionally slow metabolism.
大鲵的新陈代谢十分缓慢
Living up to 80 years, they grow into giants.
它们能活80多年，因此长得十分巨大
The fish they hunt are scarce and salamanders have poor eyesight.
可供大鲵捕食的鱼非常稀少，而且它们的视力也很差

But sensory nodes on their head and body detect the slightest changes in water pressure.
可是它们头上和身上的感官突起能觉察出最轻微的水压变化
Free from competition, these giants can dine alone.
由于没有竞争，这些大家伙得以独自享用美食
Pickings are usually thin for the salamanders,
大鲵的收获通常都比较少
but every year some of the world's high rivers are crowded by millions of visitors.
而世界上的高山河流每年都将迎接成千上万的来访者
The salmon have arrived. This is the world's largest freshwater fish migration.
鲑鱼来了。这是世界上规模最大的淡水鱼洄游
Across the northern hemisphere, salmon, returning from the ocean to their spawning grounds,
鲑鱼穿越整个北半球，从海洋回到它们的产卵地
battle their way for hundreds of miles upstream.
奋力逆流而上数百英里
Up here there are fewer predators to eat their eggs and fry.
只因上游很少有捕食鱼卵和鱼苗的掠食者。

词汇解析

1.dine alone 单独进餐
Waiter, please get that fly out of my soup. I want to dine alone.
服务生，请你将那只苍蝇从我的汤里取出来，我想单独进餐！

2.return from 从...回来
Silently, I slipped into myintended victim's room and waited for him to return from the kitchen, where he was raiding the refrigerator for leftovers.
我静静地溜到预计受害人的房间，等着他从厨房回来，他给冰箱来了个突击检查，但有没有剩下什么吃的。

视频及简介

淡水是我们最宝贵的资源，它决定了地球上生命的分布。同河流一起，从高高的山峰一路而降，直向大海，观看壮观的瀑布，在大峡谷里飞翔，在世界上最深的湖泊的冰雪下面探索野生的生命，见证动物行为的独特的、生动的一面：水獭和泽鳄将一决胜负。