My pain obvious the moment I entered the office，for the first man I met asked pitifully，“Are you feeling all right？”
A. could be
B. could have been
C. must be
D. must have been
网友回答
A. could be
B. could have been
C. must be
(答案→)D. must have been
解析：由后句的关键词：“Are you feeling all right？” 推出对过去的猜测。