辅键与其它表中的主键对应。

The secondary keys correspond with primary keys in other tables.

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你不知道坏蛋藏在哪儿，不知道去哪装武器，不知道按哪个键关闭拖拉机射线或其它东西。

You don't know where the bad guys are hiding, or where you go to reload your weapons, or what buttons you have to push to deactivate the tractor beam or whatever.

youdao

文章指出：人们并没有因为网络电视的出现而改变他们的生活，可以设想到：人们在观看现场电视转播的时候没有理由会按暂停键或者重放键，还有网络电视的按键式录像功能于其它产品功能并没有什么不同。

On paper, they do not sound life-changing: why would you want to pause or rewind live television, and what difference does it make being able to record programmes at the touch of a button?

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But because there's this lone pair here, it's pushing down on the other bonds, 5° so we end up with an angle of less than 109 . 5 degrees.

但因为这里有孤对，它会把其它键向下压，所以键角会小于109。

麻省理工公开课 - 化学原理课程节选

So, what this lets us do now is directly compare, for example, the strength of a bond in terms of a hydrogen atom and hydrogen molecule, compared to any kind of molecule that we want to graph on top of it.

因此，这让我们现在可以做到直接进行比较，比如，将一个氢原子，和一个氢分子的键的强度，与任何其它类型的分子进行比较,我们只需要把它的曲线也画在这幅图上。

麻省理工公开课 - 化学原理课程节选

So for some you that are less interested in maybe the physical structure of an individual atom, now some more exciting material for you might be coming up if you like to think about how, instead, molecules behave, either within bonding, within themselves, or with other molecules, that's what we're going to be heading to in this next unit.

那么对于某些同学，你们或许不感兴趣,对于单个原子的物理结构，现在可能有令你感到兴奋的内容,要出现了，如果你更喜欢思考,分子的行为，或者是关于成键的，或者是关于它们本身的，又或者与其它分子之间的行为，这些将是我们下个单元要讲的内容。

麻省理工公开课 - 化学原理课程节选