Yesterday evening I heard my teacher __ in the next room.

问题描述:

Yesterday evening I heard my teacher __ in the next room.
A.sang B.to sing C.singing D.to be singing
Why?

C
hear的用法有两种:hear sb.do or doing sth.
听到老师在隔壁教室说话是指那个时候听到 而不是一直在那听 所以用ing形式的