There'll be two more classes about this.

用两节课来讲它
So I'm recapitulating all that you have to know for the

我将初级和中级经济学中
purposes of this class from introductory economics and intermediate economics.

会在我们课上用到的东西总结了一下
So anything you have to know,

你需要知道的
you will hear these two classes

你会听这两节课
and some of you will find it's incomprehensible,

你们其中一些会发现很难理解
and so that's one good reason for doing it now.

这是一个现在讲它的好理由
You find out right at the beginning whether it's too complicated to bother with.

你们一开始就能知道这是不是太难学
So anyway, I'm going to keep going now to extend the model.

因此我现在要开始不断拓展这个模型了
So the biggest advance, the next advance,

最大的一步下一步
sort of, which was related to this is Adam Smith said,

与这有关的是亚当斯密说的
"How could it be that water which is so valuable has such a low price,

如此珍贵的水价格怎么会这么低