This problem is said three times.
A. having discussed
B. to have been discussed
C. having been discussed
D. to have discussed
网友回答
A. having discussed
(答案→)B. to have been discussed
C. having been discussed
D. to have discussed
解析：考查句型：Sb/Sth is said to have done,某人某物据说已经做了…，因为problem和discuss是被动关系，用不定式完成式的被动，句意是：这个问题据说已经讨论了三次了。选B。