Mary ( )breakfast at seven o'clock.

问题描述:

Mary ( )breakfast at seven o'clock.
Mary ( )breakfast at seven o'clock.括号里应该填什么,为什么?
A; is having B;has C.have
我觉得应该选B,has.但正确答案是A.is having .有人能告诉我为什么要先A吗?

at表示是在一个时间点,强调在这个时间点正在吃饭,如果一般状态加个always经常,