问题补充:
This problem is said three times.
A. having discussed
B. to have been discussed
C. having been discussed
D. to have discussed
答案:
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。