We normally think of teaching as a synchronic process, you and I are in the same place and in the same time while we are learning, when in fact at least right now we are not.

我们通常设想教学是限于一时的过程，你我在同一地点,同一时间学习，但事实上至少现在就不是这样。

麻省理工公开课 - 媒体、教育、市场课程节选

The other quick thing I want to say is that I do have office hours today from 3 to 5, so feel free to stop by if you have questions about problem-set 3 that you're finishing up.

我还想说一件小事,我今天的答疑时间是三点到五点，如果你对于第三次作业还有任何疑问,请在这个时间段来找我，不必客气。

麻省理工公开课 - 化学原理课程节选

If I gave you the location of a particle as a function of time, you can find the velocity by taking derivatives.

如果我给出物体的位移是时间的函数,你可以通过求导来得到速度

耶鲁公开课 - 基础物理课程节选

Oh, you mean my office hours?

你说的是我的办公室开放时间吗

耶鲁公开课 - 基础物理课程节选