(1) 句子结构。
本题主句的句子结构为主动宾（SVO)，主语为I ，谓语为can't understand, how 引导的 是宾语从句，其中从句的谓语feel又有that引导的宾语从句。
(2)选项词义。
A. confront vt.使面对面，使对质；遇到；比较
B. criticize vt.分析；批评；挑剔
C. control vt.控制；管理；限制；支配
D. challenge vt.质疑；向.......挑战|
句子大意为“ 我不理解他怎么会感到同事总是在责难他” 。原题的denounce为 “ 谴责， 公然抨击” 之意，与选项中的criticize词义最为接近，因此选项B 正确。
[知识拓展]词汇拓展：denounce与 criticize。
①denounce v. to say .that you disapprove of sb./sth.; to say what you do not like or think is wrong about sb./sth.
e.g. Gossip is nearly always publicly denounced, but frequently socially valued.
流言虽会受到公开谴责，却总受公众重视。
②criticize v. find fault with; express criticism of; point out real or perceived flaws
e.g. I find it difficult to criticize this position, whatever your beliefs are.
无论你的信仰如何，我觉得都很难批评这一立场。