These are just little things that can add up, so you just want to make sure you're on top of those.

这些小事情也会影响到你的总分，因此务必熟练掌握。

麻省理工公开课 - 化学原理课程节选

On top of that, there is AC Requirements and a few other things.

另外，还有AC要求和其它一些要求。

伯克利的课程计划 - SpeakingMax英语口语达人

The sense of going back and forth, no one of us on top, not correspondent in a vertical way, how things going down there.

这种来来回回的感觉，没有人是在高处，也没人在低处。

普林斯顿公开课 - 人性课程节选

A state where it's closed, so imagine a channel with a lid on top of it; when it's closed nothing can go through the channel, when it's open then things can go through.

一种是闭合状态,想想一个有盖子的通道吧,当盖子合上的时候任何东西都不能通过,而打开时就畅通无阻

耶鲁公开课 - 生物医学工程探索课程节选