Though we don’t know what was discussed, yet we can feel the topic .
A. had changed
B. will change
C. was changed
D. has been changed
网友回答
A. had changed
B. will change
C. was changed
(答案→)D. has been changed
解析：从what was discussed，可知事情已经发生。从can feel可知说的是现在的情况。应用完成时，表示过去一动作对现在造成的影响。又topic 对change是被动关系。故选D。