Once you're doing this on your own, -- especially, for example, on exam 2, which is a ways down the road, you won't be able to look at those steps, so you need to make sure that you can go through them without looking at them, but for now we can look at them as we are actually learning how to draw the Lewis structures, and rather just go through them step-by-step, it's more interesting to do it with an example.

每当你要画一个路易斯结构的时候，特别是，比如，在第二次考试中，在不远的将来，你将看不到这张表，因此你需要确保自己在不看这张表,的情况下也能按照上面的流程来画，但是目前我们是可以看着这张表,来学习如何画路易斯结构的，而相比于一步一步地讲，通过例子来演示一下会更有意思。

麻省理工公开课 - 化学原理课程节选