问题如下：
Exhibit 1. Three-Factor Model of Term Structure
Note: Entries indicate how yields would change for a one standard deviation increase in a factor.
Calculate the expected change in yield on the 20-year bond resulting from a two standard deviation increase in the steepness factor.
选项：
A.0.3015%.
B.0.6030%.
C.0.8946%.
解释：
B is correct.
考点：Managing Yield Curve Risks: Decompose the risk into three factors
解析：图1中的因子表示各个因子变动一个标准差对债券收益率的影响， 如上图，对于20年期的债券，Steepness变动一个标准差收益率变动为-0.3015%，因此steepness增加两个标准差，将导致20年期债券的收益率下降0.6030 ％，
Change in 20-year bond yield = -0.3015% ×2 = -0.6030%.
老师，为什么要乘以2？没明白用的知识点
