If you decide to opt in by a pass fail, I just need to sign your white study card or if you wanna decide before the 5th Monday, just grab the pink slip and I can sign that and you can turn that in at any point and I'm happy to chat during break today or after class if you have any questions or concerns.

如果你上我们的课程只是要一个分数，那么我只需要在你的白卡片上签个名就可以了,或者说，如果在第五周的周一前还没考虑好，把你的解聘书拿来，只要我签个字,任何时候你都开以离开我的教室,当然，如果你有任何问题和疑虑,我也很高心和大家做课下交流。

哈佛公开课 - 计算机科学课程节选

So, Lewis structures are really a model for a way to think about what the valence electron configuration is, and as I said, it's not based on quantum mechanics, it's something that Lewis observed far, far before quantum mechanics were discovered.

路易斯结构实际上是一个用来考虑价,电子排布的模型，而就像我说的，它并不以量子力学为基础，而是路易斯在以前发现的,在量子力学出现很早前。

麻省理工公开课 - 化学原理课程节选