I'm really liberal, but this disturbs me because I am looking at you, I'm trying to see from your reaction how much of my lecture you are following, and then it's very distracting when people are talking.

很无所谓的,但是我很不喜欢有人说话,因为我正看着你,我要根据你的反应来判断,我的课你听懂了多少,但是如果有人说话的话,就会让大家分神

耶鲁公开课 - 基础物理课程节选