a few minutes later, i ____at the door and an old man_____it.

题目

a few minutes later, i ____at the door and an old man_____it.
A.knocks ;opening B.knocked ;opened
C.knock ;open D.knocking ;opening

答案

答案：B
I 后跟谓语动词,排除 D,而 and 连接的并列句左右时态要保持一致,所以都用一般过去时 knocked,opened
不明白的再问哟,请及时采纳,多谢!