问题如下：
2. The events of 2004 to 2006 would be expected to:
选项：
A.bias the historical equity risk premium estimate upwards.
B.bias the historical equity risk premium estimate downwards.
C.have no effect on the historical equity risk premium estimate.
解释：
B is correct.
The events of 2004 to 2006 depressed share returns but 1) are not a persistent feature of the stock market environment, 2) were not offset by other positive events within the historical record, and 3) have led to relatively low valuation levels, which are expected to rebound.
是因为depress stock return 并且以后会涨回来，所以低估ERP吗？ERP就是股票return超过无风险收益率的部分吧？
