The idea of making as Asian-Pacific operational center
(A)
of information of Taiwan had been under discussion for
(B)
years, and many have cast doubts upon its viability.
(C) (D)
(A) making as
(B) had been
(C) , and
(D) upon
抱歉不会画底线，所以选项打出来
为什么答案是B呢？
谢谢

答案确定是B吗?

has been

个人浅见，不正确请纠正： A. of 介系词后动词改动名词。B. 被讨论好几年（可能已经讨论完，或是还在讨论，不确定先往后看。C. 连接词前后都是完整句子，加逗号正确。D. 我觉得语意正确，在这件事上的可行性（换on 好像也可以）。回到B，第二个对等句是现在是，所以这件事还在讨论，答案B。