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Listen to a conversation between a student and his biology professor.
听一段学生和生物学教授的对话。
Well, you know, I'm reading the papers about whales, and the path they travel as they swim through the ocean, their migration patterns.
你知道的，我正在看关于鲸鱼的论文，关于它们游过海洋的旅行轨迹，它们的洄游模式。
Yes, I remember.
对，我记得。
Well, I was thinking about it, and I realized I don't understand how they hold their breaths under water.
我正在想这件事，我发现我不明白它们怎么在水下闭气的。
It's a little crazy for me to be writing a paper about migration patterns without actually knowing how they stay underwater for so long.
让我写一篇关于它们洄游模式的论文，但我实际上却不知道它们怎么在水底待这么长时间的，这有点疯狂。
Did you do any research to find out how they do it?
你有没有查过资料来弄明白它们怎么做到的？
Yeah, I did.
我有。
I searched on the Internet, and there was a lot of information about whales, their habitats, the way they communicate, you know, their songs.
我在网上搜索过，网上有很多关于鲸鱼的信息，它们的栖息地，它们的交流方式，你知道的，它们的歌声。
But if there was anything about whales and how they hold their breaths, I missed it.
但假如真的有关于鲸鱼怎么憋气的信息，我一定是看漏了。
I've got a bunch of books. Actually, I've got so much information, it's a little overwhelming.
我有一大摞书。事实上我掌握了大量的信息，有点太多了。
I'm surprised that there is nothing about it in any of those books.
我很惊讶在这些书里竟然没有与此相关的信息。
Well, to be honest, I've only skimmed them so far.
坦白说，我才刚把它们粗看了一遍。
I'm still working on finding sources.
我还在寻找信息。
Ok, I know I encourage everyone in class to look at a substantial number of sources, but I don't want you to get overwhelmed.
好了，我明白我鼓励班上的每个人去看大量相关资料，但我不想你看太多以致无从下手。
Looking at a number of sources gives you a good knowledge base, but students only have a limited amount of time to work on each paper.
通过看一定数量的资料，你会得到一个很好的知识储备，但学生在每份论文上都只有很有限的时间。
I don't expect you to read a dozen of books on whales for this assignment. Focus on just a few.
我不希望你为了这次作业看一大堆关于鲸鱼的书。集中看几本就行了。
Ok, thanks.
好的，谢谢。
You know, since you're already here, I can give you a quick summary of how whales hold their breaths underwater.
既然你已经来了，我能给你简单讲讲鲸鱼是怎么在水下闭气的。
It's just a matter of certain adaptations in their anatomies, specifically in their circulatory system.
这不过是它们身体构造里的一些适应性进化，准确地说是它们的循环系统。
So, the blood flow was what makes the difference?
所以血流是关键？
Yes, and in a couple of ways.
对，通过不同的方式。
First, blood makes up a larger share of a whale's weight than any other mammals.
首先，血液在鲸鱼体重中占的比重事很大的，比任何其它哺乳动物都要大。
So they can store more oxygen because they have more blood?
所以鲸鱼能储更多的氧，就因为它们的血量更多？
Yes, but that's only part of it.
对，但这只是一部分原因。
They also have a greater capacity than land animals to store oxygen in their blood.
它们在血内储氧的能力比陆生动物高出许多。
So how does having more oxygen in their blood help them stay underwater longer?
那么，拥有更多的血液是怎么帮助它们在水下待得更久的？
It's the way the whale's blood carries oxygen to the rest of its body.
这是靠鲸鱼血液将氧气运输到身体其它部分的方式。
Whales carefully conserve their oxygen when underwater in a couple of ways.
当在水下时，鲸鱼通过不同的方法谨慎地储氧。
When a whale dives, its metabolic weight drops, causing its heart beat to slow down.
当鲸鱼潜入水中时，它的代谢体重会下降，心跳随之减缓。
And the blood flows to its muscles and some of its none-vital organs, like its kidneys, is also cut off.
而且通向肌肉和一些非要害器官（如肾脏）的血流也停止了。
Whales muscles and none-vital organs are able to function without oxygen for an extended period of time.
鲸鱼肌肉和非要害器官能在缺氧情况下持续运作一段时间。
I see, well, now I can concentrate on my topic.
我懂了，现在我我能专注于我的课题了。
