题目

a.We were watching TV when we heard the door____
b.We were watching TV when we heard someone____at the door(knock)
老师说第一个是knocked,我认为不是heard do和heard doing么?这儿听到敲门完整是动作不是用do么?加上是被动,所以我觉得是be knocked
第二问老师说是knock,同样,我觉得听到有人敲门时完整动作,不是片段啊,为什么用doing而不用knock?

提问时间：2020-07-31

答案

呃,第一句是这样的,这是一个省略句,完整地应该是 we were watching Tv when we heard the door be knocked,在这里be 可以省略,所以就成了knocked第二句,因为前面有个 we were watching tv,用的是过去进行时,说明强调...