问题补充:
It is really a pity that I can not attend your wedding party this weekend. I a very important international conference in Paris then.
A. have attended
B. are attending
C. have been attending
D. will be attending
答案:
A. have attended
B. are attending
C. have been attending
(答案→)D. will be attending
解析:句意:这真的是一个遗憾,这个周末我不能参加你的婚礼。届时我将参加一个在巴黎的非常重要的国际会议。这里的时间是then,也就是这个周末对方的婚礼,所以是过去的某个时间正在做的事情,用过去进行时,所以选D。