Now if you read in the book, you read about where this figure is shown in the book, you can understand more about why these structures line up in the right way so that the right molecular elements are together to form hydrogen bonding pairs between them.

如果你预习过课本,课本中有关于这些详细的描述,你可以更深刻的理解,为什么这些结构是采用这种连接方式,以使对应的分子部分靠近,并形成氢键连接

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that's one way to think about it, and there's also another way, and this is the way that your book presents it. If you, in fact, have two of the same atom right next to each other, let's say you have a crystal, or let's say you're talking about a metal, what you can do is just look at the distance between the two nuclei, and split that in 1/2, and take the atomic radius that way.

这只是一种定义的思路，另外还有其它方法，也就是你们课本上的方法，如果你，事实上，有两个相同的原子彼此靠在一起，比如说你有一个晶体，或者说你讨论的是一个金属，你所要做的就是,看看这两个原子核之间的距离，然后将距离除以二，就得到了这个原子的半径。

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