Question

To my disappointment，when I got to the booking office，they________all the tickets．

1. A.
   sold
2. B.
   were selling
3. C.
   would sell
4. D.
   had sold

Answer 1

D
分析：这是一个含有when引出的时间状语从句的复合句，应该以所给got为基点，判断另外一个动作(sell)和got之间的时间关系，由to my disappointment的意思，可以判断出sell发生在got之前，也就是“过去的过去”，要用过去完成时。