---There anybody in the room.
--- Why do you say so?
--- Because the door is locked.
A. must not be
B. can’t have
C. can’t be
D. may not be
网友回答
A. must not be
B. can’t have
(答案→)C. can’t be
D. may not be
解析：考查情态动词表推测的用法。must表推测用于肯定句中，可排除，can表推测用于疑问句或否定句中，may表示可能性的推测，根据答语的内容可知是绝对否定的回答，是对现在事情的推测，故选C