--- Did they attend the opening ceremony?
---They _, but they were late and quit it.
A. would
B. would have
C. didn't
D. will have to
网友回答
A. would
(答案→)B. would have
C. didn't
D. will have to
解析：句意：--他们参加开幕式吗？--他们本想参加，但是他们迟到了，就放弃了。这里根据but后的内容可知他们没有参加开幕式，所以空格处表示过去想做的事情没有做，是一种虚拟，故用would have done，这里把attended the opening ceremony省略了，故选B。