Why didn’t the girl go to the movies?

M: Do you want to see a film tonight
W: I can’t. I have to review my lessons.  
M: Are you having a test tomorrow
W: Yes. We’re having our mid-term test.
M: I wish you good luck.
W: Thanks a lot. But I’m a little nervous.
M: Nervous You used to study very well.
W: But I haven’t studied for a long time.