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本影片片段来自《非洲》

The lower mandible of their beaks is greatly elongated.
他们的下喙长得非常长
They slice it through the surface of the water at ten metres a second.
他们能以每秒十米的速度划过水面
If and when it hits a tiny fish, it'll snap shut.
当下喙碰到小鱼时 会立刻合上
But why come up river to these open sand flats?
但为何要逆流而上到这片开阔的沙滩来呢
This is the answer.
这就是答案
But this nursery will not exist for long.
但这个托儿所无法长期存在
Four weeks from now, it'll be under ten metres of water.
再过4周 这里会被十米深的河水淹没
If by then these chicks can't fly, they will drown.
若到那时幼鸥仍不会飞 就会被淹死
The problem for young skimmers is that when they hatch,
幼小的剪嘴鸥在破壳而出时
the lower part of their beaks is the same size as the upper.
他们的下喙跟上喙一样长
While they wait for it to grow,
等待下喙长长的同时
they do their best to learn the skimming technique.
他们会努力学习捕食技巧

重点解释

But why come up river to these open sand flats?但为何要逆流而上到这片开阔的沙滩来呢

come up升起；靠近，走进

His new book did not come up to expectation.

他的新作没有达到预期水平。

You've come up in the world, haven't you?

你的地位已经上升了,是吗?

But this nursery will not exist for long.但这个托儿所无法长期存在

exist有时有“在逆境中生活，仅能活命”的意思。

Some people in some poor countries receive wages that allow them to exist but not to live.

有些贫困国家的人民的收入只能勉强维持生计。

exist与subsist区别：subsist指“继续存在”，而exist指“存在”。

While they wait for it to grow,they do their best to learn the skimming technique.等待下喙长长的同时他们会努力学习捕食技巧

wait for 等候； 等待

It irks us to wait for people who are late.

等候迟到的人使我们厌烦。

He was then sitting on thorns and waiting for you.

他当时如坐针毡，焦急地等待着你。