There's a cluster of cells here, there's a sheet of cells that forms an outer lining, and what is most noticeable is this cavity, this fluid filled cavity which begins to develop.

有一簇细胞,一层细胞构成了外形轮廓,最明显的结构就是这个空腔,这一充满液体的空腔开始发育形成

耶鲁公开课 - 生物医学工程探索课程节选

Keep in mind we do have this p orbital here and it's coming right out at us. And this p orbital is here, but it's empty, it doesn't have any electrons in it, that's why we don't have to worry about it in terms of getting our electrons as far away from each other as possible.

他们程120度角互相远离,这样它们离得最远，记住我们这里确实有个p轨道，它朝向我们，这里有个p轨道，但它是空的,里面没有电子,这就是为什么我们在考虑。

麻省理工公开课 - 化学原理课程节选