答案好多：比如
(1/16)+(7/8)=15/16
(1/8)+(13/16)=15/16
(3/16)+(3/4)=15/16
(1/4)+(11/16)=15/16
(5/16)+(5/8)=15/16
(3/8)+(9/16)=15/16
(1/2)+(7/16)=15/16