[学习疑问] Level 1 notes中的AD和AS还有philips curve几个问题，请大家帮忙解答一下，多谢！

<1>level 1 notes P176 第2题：

For a demand-pull effect or a cost-push effect to cause inflation:

A the AD curve has to shift in  response to a shift of the AS curve

B the cause of the shift in AD or AS must be repeated or sustained

C economic equilibrium must be re-established at a higher price level

答案为B，不解之处：请问C选项错在哪里呢？好像notes P168-169页中的两个图确实都是最后价格都高了

<2>level 1 notes P170 Figure 2：long-run and short-run philips curve

不解之处：请问何时short-run philips curve会在PC1到PC2这样整条线上下浮动？何时会只在PC1上的1和2点之间浮动？何时long-run philips curve会左右浮动？看了书半天没明白。