After a knock at the door, the child heard his mother’s voice him.
A. calling
B. called
C. being called
D. to call
网友回答
(答案→)A. calling
B. called
C. being called
D. to call
解析：V-ing作宾语补足语的用法。解析：V-ing常接在感官动词如hear, see, catch, find, smell, feel和某些表“致使”意义的动词keep, have, leave等后作宾语补足语。由题干中的hear可知，空格内应填calling。