answer: Kasy can't attend Jonason's birthday party because of the exam. Jonason will hold the party ahead of time.
documents: #Person1#: Hello, this is Jonason speaking.
  #Person2#: Hello, Jonason, I am Kasy. I am sorry to tell you that I may not attend your birthday party this weekend.
  #Person1#: Oh, what's up?
  #Person2#: Nothing much.., but...
  #Person1#: What's happened then?
  #Person2#: I have an important exam at that time.
  #Person1#: If so, I think we can hold the party ahead of time. What do you think about it?
  #Person2#: Yeah, It is a good idea. I can't agree more.
  #Person1#: Great and I wish you success.
  #Person2#: Thank you, happy birthday to you.