To my surprise he turned up in the room without .A. noticedB. being noticedC. noticingD.

问题补充：

To my surprise, he turned up in the room without .

A. noticed

B. being noticed

C. noticing

D. to be noticed

答案：

A. noticed

(答案→)B. being noticed

C. noticing

D. to be noticed

解析：介词without后面跟名词或动名词,这里用动名词的被动形式.being noticed