When you only have one classroom, but you have four different classes, you can only separate them by benches.

VOA: standard.2010.02.25

What have we done over the last three or four lectures? We've started introducing you to classes of algorithms. Things that I'd like you to be able to see are how to do some simple complexity analysis.

我们在过去三节或四节课中讲了什么？,我开始向你们,介绍算法的类型,我想你们知道的是,如何做一些简单的复杂度分析。

麻省理工公开课 - 计算机科学及编程导论课程节选

where I would have, I think four classes one after the other on Wednesdays.

在那一段时间，我在周三会连续上四节课。

耶鲁的忙碌生活 - SpeakingMax英语口语达人