问题如下：
The effective annual yield of an investment is 9%. What is the yield on a bond-equivalent basis?
选项：
A.8.8%
B.4.4%
C.9.0%
解释：
A is correct.
The first step is to convert the EAY to an effective semiannual yield: (1+9%)0.5-1=4.403% ;
the second step is to double it: 2×4.403%=8.806%
老师原版书里面这段，in this zero coupon, 2.2565% compounded two times a year,1.1220% compounded four times a year, 0.3726% compounded twelve times a year are all equievlant to an effective annual rate of 4.5640%. 是怎么换算的啊？比如用（1+2.2565%／2）^2-1 也不等于4.5640%啊
