So you might imagine that the crust forms a solid, complete shell, like an eggshell around a softer inside.
所以你可以想象成地壳形成了一个坚实的完整的外壳,就像蛋壳包裹着更软的内部一样。
可汗学院:生物化学
It's only one away from completing it's shell.
离完成它的外壳只有一步之遥。
可汗学院:生物化学
The last thing it wants to do is give away electron, it wants an electron really, really, really, really badly so it can get to a configuration of argon, so it can complete its third shell.