如果不明白，课后来问我。

Please see me after class if you don't understand.

youdao

如果不明白这之间的差异，那么这个人就是虚伪的、无理性的、不合逻辑的。

If one does not understand the difference, then that person is disingenuous, irrational and illogical.

youdao

如果你不明白一个问题的答案，就请医生再解释一遍，直到你明白为止。

If you don't understand the answer to a question, ask the doctor to explain it again until you do understand.

youdao

If you have any questions, anything that's not clear, if you agree or disagree with something, email me or email your TF and we'll always respond.

如果你有任何问题或不明白的地方，如果你同意或反对什么观点，请给我或助教写邮件,我们一定会回复的。

哈佛公开课 - 幸福课课程节选