Final question Tom, and this is from a viewer who send in the question by Twitter,to be submitted to you.

最后一个问题，这是一个观众的提问,通过twitter网站，提交给你。

斯坦福公开课 - 经济学课程节选

I'm not going to have you work long hours on difficult problems to be submitted and then graded.

我的作业不会让你们花费大量的时间,去钻研很难的问题，然后交上来让我打分。

麻省理工公开课 - 固态化学导论课程节选