--I'll be able to come to see your performance at 8:30tomorrow evening.--I'm sorry ,by then my performance()and I()reporters in the meeting room.Awill be ended ;will meet B is to end ；will meet C will have ended ;will be meeting D will be ended ;am going to meet选Cwhy
--I'll be able to come to see your performance at 8:30tomorrow evening.
--I'm sorry ,by then my performance()and I()reporters in the meeting room.
Awill be ended ;will meet B is to end ；will meet C will have ended ;will be meeting
D will be ended ;am going to meet
选Cwhy
c
by +时间点 用完成时，这里then是将来的时间，所以用将来完成时
第二空，推测出，它省略了说话人都清楚地时间状语at 8:30tomorrow evening，所以用将来进行时，那个时间点我应该正在会议室会见记者们
将来进行时主要表示将来某一时间正在进行的动作,或表示要在将来某一时 将来进行时间开始,并继续下去的动作.常用来表示礼貌的询问、请求等.如：This time next day they will be sitting in the cinema.将来进行时常用的时间状语 Soon,tomorrow,this evening,on Sunday,by this time,tomorrow,in two days,tomorrow evening,By this time tomorrow,I'll be lying on the beach.等等.
by then -- 到那时一般与现在完成时连用.但是上文是8:30tomorrow evening,所以时态是将来完成时.利用排除法就选c 如果要问 my performance是否为承受者的话,我自己觉得这里作主语,不是被结束的意思.
答案是 C
tomorrow evening. 是将来的时间，自然要用将来形式，而且，performance 是被演的，所以要用被动语态。
后面的那个，指的是那个时间，将会有一个会议，所以要用进行时态、
希望能后帮助到你！~~~