The simile sets out to establish the moral polarities between good and evil, but it then works almost systematically to undo that understanding.

这里的比喻开始创造出善与恶之间的,两极性，然而后来它又几乎自动的抹去了这种理解。

耶鲁公开课 - 弥尔顿课程节选

We can say that a nonpolar molecule you can have as a result of two different conditions.

所以你可以说非极性分子,有两种构成方式。

麻省理工公开课 - 固态化学导论课程节选