It also is a good lesson in how difficult it is, and we'll talk about this in a subsequent class, to actually measure what people eat.

同样这能很好的说明,实际评价人们的饮食有多困难,我们下节课会讨论这个话题

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选

I have trouble understanding them

我有困难理解他们的课，

热情的教授 - SpeakingMax英语口语达人