David may ___________, but we must go at once.

David may ___________, but we must go at once.
A、stay late
B、stay lately
C、have stayed late
D、stayed late
【正确答案】：A
【题目解析】：根据but后面的must可指知前半句用一般现在时，stay late意为”待到很晚“；may是情态动词，意为”可能“，其后要接动词原形，故选A。