— Can you come to my birthday party tonight? — I’d love to but I on a patient at 6 o’cloc

问题补充：

— Can you come to my birthday party tonight?

— I’d love to, but I on a patient at 6 o’clock.

A. will operate

B. am operating

C. will be operating

D. will have operated

答案：

A. will operate

B. am operating

(答案→)C. will be operating

D. will have operated

解析：特指“今晚六点钟这个时候给病人做手术”，用将来进行时。将来进行时用于将来某个时刻正在发生的动作。句意：——今晚六点钟你能来参加我的生日晚会吗？——我倒是很想来，不过晚上六点我将在给一个病人做手术。