I’m afraid by the time you arrive this afternoon I a lesson then.
A. had
B. are having
C. have had
D. will be having
网友回答
A. had
B. are having
C. have had
(答案→)D. will be having
解析：句意：恐怕咋你今天下午到的时候，我将正在开会。时间是then=this afternoon，是将来时间，而且根据句意，在那时是正在开会，用将来进行时，选D。