So this is a thing, Week Number Four, saw very commonly, which was -- this is something we saw commonly and there's a couple of issues here.

所以这是一件事，第四个，一般的分解，那是我们讲解的东西,这里有好几个问题。

哈佛公开课 - 计算机科学课程节选

This is the end of week four.

这个第四周最后一次课。

哈佛公开课 - 计算机科学课程节选