问题如下：
For a technical analyst who uses past prices and volume to predict future prices, what's his assumption about the market efficiency?
选项：
A. The market is semi-strong-form efficient.
B. The market is weak-form inefficient.
C. The market is weak-form efficient.
解释：
B is correct.
Based on the weak-form efficient hypothesis, investors cannot earn abnormal returns by trading on the basis of past prices and volume. So technical analysts assume that markets are weak-form inefficient.
老师，这道题问的只是他用了价格等手段去判断，并没有说失败，为什么不能是弱有效市场呢？
