选择 （ ）someone knocket____the door while I____ my breakfast A.on;had B.at;were harving C.on;amC.on;am having D.at;was having
问题描述：
选择 （ ）someone knocket____the door while I____ my breakfast A.on;had B.at;were harving C.on;am
C.on;am having D.at;was having
答
”knoked“？
一般如果knock用作动词时，用on,
如果knock用作名词时，用at.
没有太绝对的区别，只是一般这样使用
eg:
Did I hear a knock at the door?
Please do not enter before knocking on the door.
Ans:on, was having
答
D
敲门 know at the door 固定搭配
所以AC不对
主语I,单数,所以用was having
当有人敲门时,我正吃早饭.