OK, well.I'll try to explain this, This is a picture that was taken about 50 years ago.

好吧，我试着来解释一下，这张图片大概是50年前拍的。

斯坦福公开课 - 7个颠覆你思想的演讲课程节选

.. Ok, so... I think I don't need to explain to you why there is one lecture in the semester that I don't teach and Sean will teach it.

好的，那么。,我想我不需要跟你们解释,为什么这学期有一节课不是我教而是Sean教的。

哈佛公开课 - 幸福课课程节选