someone____at the door while Tom was having his supper.A.was knoc_英语解答

someone____at the door while Tom was having his supper.
A.was knocking B.has knocked C.is knocking D.knocked 我选的A,但老师说是错的.是否选D?若是when结果是否不同?

人气：149 ℃　时间：2020-04-24 11:49:23

解答

的确选D
while后面才接ing形式,而这里因为是过去发生的所以用过去时