A.fff\((1+\frac{1}{2})-\frac{1}{20}\)/fff
B.fff\((1+\frac{1}{2})-(\frac{1}{21}+\frac{1}{22})\)/fff
C.fff\(1-(\frac{1}{20}+\frac{1}{22})\)/fff
D.fff\(1-\frac{1}{22}\)/fff
E.fff\(\frac{1}{20}-\frac{1}{22}\)/fff
我的答案：
