Question

【题目】I heard someone ________ at the door. I opened the door and found a postman outside.

A. knocks B. knocking

C. to knock D. knocked

Answer 1

【答案】B

【解析】

句意：我听见有人敲门。我打开门，发现一个邮递员在外面。hear sb. doing sth. 听到某人正在做某事；用动名词做宾补。故选B。