And you'll say, "What?" I mean, they've kept this from you. You look at them and say,

你说，“天哪！”原来他们一直瞒着你。你看着他们说，

How long课堂 - SpeakingMax英语口语达人

Course assistants as we use the jargon are alumni of CS50 who return to the course for a couple of hours a week having taken it in prior years, to help you, the newest batch of students, one on one with office hours, with problem sets; and similarly do the CS function as they might in many courses.

课程助理用我们的行话说就是CS50校友0,他们在前几年一直都是一周回来几个小时,来帮助你们这些新生，在上机的时候以一对一的方式，帮助你们完成这些问题集,在很多其他课程中他们也是这么做的。

哈佛公开课 - 计算机科学课程节选

and that you have been paying attention by saying politely,

你一直在听着他们说的内容,然后有礼貌地说，

It sounds like 课堂 - SpeakingMax英语口语达人