It was the first time Mary such a big opening ceremony.
A. has attended
B. attended
C. had attended
D. should attend
网友回答
A. has attended
B. attended
(答案→)C. had attended
D. should attend
解析：句意:那是第一次玛丽参加了这么大的开幕式。这是固定句式：It was the 序数词+time that …had done，如果这里用is这个动词that后用have done，故选C。