It was quite a long time I figured out what had happened to the manager.
A. after
B. before
C. when
D. since
网友回答
A. after
(答案→)B. before
C. when
D. since
解析：句意：有很长时间我才弄清经理发生了什么。这句话用了固定句型：It was+一段时间+before+从句，表示“过了很长时间才/就….”如果是It is+一段时间+since…，自从…有多久了，选B。