微观经济学还是这道题, 只要答案D  要详细准确的答案,有图更好. 这是问题D 的提示.1.understan

微观经济学

还是这道题, 只要答案D  要详细准确的答案,有图更好. 这是问题D 的提示.

1.understanding of the link between opportunity cost, marginal cost and supply curve.

2What does the PPFs look like for Rivendell and Moria?

3Does it follow the theory of a true PPF (ie what a real PPF should look like)?

4If they are different, why are they different?

5The question is asking you to compare and explain the difference or similarities 

6The question is asking you to compare and explain the difference or similarities between a theoretical  PPF and what PPFs of Rivendell and Moria.

不是定义的问题,主要是还是要理解的,用你自己的话回答.  谢谢你了.

这题的题点,如提示说的,在于increasing opportunity cost上.这也是为什么一个理论上的PPF是一个向外凸出的图像.我们的这题里精灵和矮人城市只生产两种产品mail和sword.他们面临的是fixed opportunity cost,所以,实际的PPF是直线.具体解题思路如下：
首先,把我之前给你画的俩个城市的PPF画出来.然后,评价说,两个PPF不是向外凸出的曲线,而是直线.
这与我们经常见到的理论存在的PPF是不相符的.（可以画一个理论PPF的图,书本上那种向外凸出的PPF曲线）.这种向外凸出的PPF曲线,主要是因为opportunity cost是increasing的.This implies as an economy increases its production of any good along its PPF, the cost of obtaining an additional unit of the good will be increasing.我们精灵和矮人城市是另外一个story.因为,我们精灵和矮人城市只生产两种产品 sword and mail.The opportunity cost that Rivendell and Moria face is actually fixed. Take Rivendell for an example, increasing the production of one unit mail cost Rivendell precisely 3 units of sword and this cost is fixed despite how many mails Rivendell is currently producing (within its production capacity, of course)因为两个城市面临的opportunity cost都是fixed的,所以,他们的PPF是直线.而非正常的外凸的PPF.This is also why the PPFs of Rivendell and Moria are possible.

再问： 麻烦能总结一下，直接回答D 部分吗？
再答： The PPFs for Rivendell and Moria are presented in the following figure:

【画第一个图，我们之前讨论过的RIVENDELL和MORIA的PPF。两条直线PPF的那个图】
As we can see, the PPFs are straight lines without any curvature, which is different from the PPF that we usually see. An ordinary PPF usually takes the following form:
【画第二个图，一个我们最常见的向外凸出的PPF曲线。】
This bow-shaped PPF is caused by increasing opportunity cost. As an economy increases its production of any good along
its PPF, the cost of obtaining an additional unit of the good will be
increasing.

However, this is not true for our Rivendell and Moria. Swords and mails are the only two products for both cities. The opportunity cost that Rivendell and Moria face is actually fixed.
Take Rivendell for an example, increasing the production of one unit
mail cost Rivendell precisely 3 units of sword and this cost is fixed
despite how many mails Rivendell is currently producing (within its
production capacity, of course)

【字数超了，剩下部分看评论】