听力原文:M: This physics assignment was difficult. I worked all night and couldn't finish
W: You worked all night? It took me only twenty minutes.
Q: Why is the woman surprised?
(16)
A.She found the assignment very difficult.
B.The assignment was difficult to complete in 20 minutes.
C.She finds it hard to believe the man spent so long a time.
D.The man couldn't finish the assignment because he had other work to do.