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

Not the soul can't be destroyed or if it can be destroyed, it is very very hard and takes very very long time.

而不是灵魂不会毁灭，或者,如果可以毁灭，毁灭会很难,需要很长时间。

耶鲁公开课 - 死亡课程节选

Sometimes, when the ideas of political philosophers are as familiar as Locke's ideas about consent, it's hard to make sense of them or at least to find them very interesting.

有时当一些政治哲学家对同意的看法,与洛克非常相似时，都让人很难理解,或至少不会觉得很有趣。

耶鲁公开课 - 公正课程节选

This is not meant to be difficult.

这个作业不会很难

耶鲁公开课 - 心理学导论课程节选

There're also changes of what you can teach, extends what you can teach, because you can get to concept which are really quite sophisticated that you will never teach it at the introductory level, because the math is the least that you can make it quantitatively, because you have a visualization that shows physically what's going on.

同时这也能改变,教学内容，你能教授的程度，因为你可以定义,那些通常很难的,你在入门阶段都不会遇到的,抽象阶段，因为数学是你最不能,用定量手段来解决的，因为你有一个直观过程,知道什么正在进行。

麻省理工公开课 - 媒体、教育、市场课程节选