The moment the 28th Olympic Games ____ open, the whole world che

The moment the 28th Olympic Games ____ open, the whole world cheered.
A、declared
B、have been declared
C、have declared
D、were declared
【正确答案】：D
【题目解析】：第28届奥林匹克运动会宣布开始的时候，全世界都在欢呼。