听力文本

At dawn, the first adult midges start to break out.
黎明时分，第一只成蚊破蛹而出
Soon, millions upon millions of newly-hatched lake flies are taking to the wing.
不久，成百上千万只新羽化的幽蚊全都扇动着翅膀飞到空中
Early explorers told tales of lakes that smoked as if on fire.
早期探险家看到这种湖面上“冒烟”的情景，还以为是湖底着了火
But these spiralling columns, hundreds of metres high, are mating flies.
这些高达数百米的螺旋型“烟”柱，其实是正在交配的幽蚊
0nce the flies have mated, they will all drop to the water surface, release their eggs and die.
幽蚊完成交配之后，便会一起落到水面，产下卵，然后死去

Malawi may look like an inland sea, but it's dwarfed by the world's largest lake.
马拉维湖看起来像大海一样辽阔，但它远比不上世界上最大的湖泊。
Baikal in eastern Siberia.
东西伯利亚的贝加尔湖
Four hundred miles long and over a mile deep,
贝加尔湖长400英里，深度超过1英里，
Baikal contains one-fifth of all the fresh water found in our planet's lakes and rivers.
其中的淡水储量占到了全球江河湖泊淡水总量的1/5
For five months of the year, it's sealed by an ice sheet over a metre thick.
每年中总有5个月，湖面被1米厚的冰层覆盖。

词汇解析

1.break out 向外打破(门等)
They broke the windows out to escape from the fire.
他们把窗户往外砸破，安全逃出了大火。

2.millions upon millions 成百上千万
Millions upon millions of animals every year are being severely abused, caged, starved, abandoned, hunted, killed, and slaughtered all over the planet.
地球上每年都有千百万动物被残酷虐待，被囚禁，被饿死，被遗弃，被追捕，被杀死，被屠宰。

3.be dwarfed by 相形见绌
Whatever the number, it will be dwarfed by the damage to Alibaba's reputation.
不管这个数目有多大，它与阿里巴巴的声望损失将是相形见绌的。

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。