My pain obvious the moment I walked into the room, for the first
man I met asked me pitifully: Are you feeling all right?
A. must be
B. must have been
C. could be
D. could have been
网友回答
A. must be
(答案→)B. must have been
C. could be
D. could have been
解析：本题是情态动词的考查。根据后半个分句可以知道谓语动词发生于过去，而情态动词+动词的完成式表示对过去的推测。