问题补充：
-Have you got the airplane tickets?
-No, because its May Day ,all the tickets to Beijingout.
A. have been sold
B. had been sold
C. bad sold
D. were being sold
答案：
(答案→)A. have been sold
B. had been sold
C. bad sold
D. were being sold
解析： 本题考查的sell out 的被动语态，用于现在完成时，故选A
