Question

【题目】— Listen! Somebody is ___________ at the door.
— Don't answer the door! Mom doesn't let us do it while she is out.
A.standing
B.knocking
C.sitting
D.greeting

Answer 1

【答案】B
【解析】句意：——听，有人正在敲门。——不要开门。妈妈出去时不让我们这样做。standing 站立；knocking敲打；sitting坐；greeting向……问好。由语境可知，敲门的动作正在发生，因此要用现在进行时，故选B。