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这三种最重要的营养循环包括氮循环、碳循环和我们今天要讲的磷循环。

The three most important nutrient recycles are the nitrogen cycle, the carbon cycle and the one we are going to talk about today, the Phosphorus cycle.

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第三种是某些基本的化学物质，如碳、氧和氮。

A third is certain basic chemicals such as carbon, oxygen and nitrogen.

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This is very easy molecule because we know exactly where to put them without even having to think, we only have one option, and we'll make a triple bond between the carbon and the nitrogen.

这个分子非常简单,因为我们知道应该把它们放在哪里,甚至不用去想，我们只有一个选择，我们将在碳与氮之间形成一个三键。

麻省理工公开课 - 化学原理课程节选

So, for example, down here I wrote that it was n 2 and that it was h 2, but when I re-wrote the molecules up here, you saw that it's an h h single bond where it's a nitrogen-nitrogen triple bond.

比如，在这下面我写的是氮分子2,而这个是氢分子，但我在上面把这些分子的形式改写了，大家可以看到,这是一个氢与氢之间的单键，含一个氮与氮之间的三键。

麻省理工公开课 - 化学原理课程节选

- Then also, nitrogen, 3 minus -- these are all going to be isoelectronic with neon.

然后还有，氮，负三价-,这些都是与氖原子等电子的。

麻省理工公开课 - 化学原理课程节选