-----Did Mary come to the party?---I don’t knowShe while I was out．A. may have comeB. mus

问题补充：

-----Did Mary come to the party?

---I don’t know．She while I was out．

A. may have come

B. must have come

C. might come

D. could come

答案：

(答案→)A. may have come

B. must have come

C. might come

D. could come

解析：这题考查情态动词的完成式的用法：从第一句话知道是指过去的事，从-I don’t know，知道是可能已经来了。用may have come，A项正确。