The feeling of just being free to wake up whenever you want after waking up early all week,

那种能睡到自然醒的感觉，在一整周不得不早起以后，

I like实战 - SpeakingMax英语口语达人

Right now at this point in our course, whenever you have a problem where there is some body and someone says, "Write all the forces on it", what you have to do is very simple.

现在在我们这个课程里,如果你遇到一道题目,题目给了你一个物体,并要求你,"写出该物体所受的所有力",你要做的其实很简单

耶鲁公开课 - 基础物理课程节选