He said they were responsible for the present problem.

VOA: special.2009.07.16

And so they each had to present... Each one wrote a term paper on one problem.

那么每个学生都要。,每名学生都要就一个问题写期末论文。

普林斯顿公开课 - 人性课程节选

So, we are now going to do one standard problem where we will convince ourselves we can apply this formulas and predict the future given the present.

我们接下来将去研究一个标准问题,通过这个问题,我们能让自己相信,我们能利用这些式子,根据现状,预测未来

耶鲁公开课 - 基础物理课程节选