answer: #Person1# wants to change a seat with #Person2# because #Person1# wants to sit beside #Person1#'s friend. #Person2# agrees.
documents: #Person1#: Excuse me. Can I change my seat with you? I want to sit beside my friend.
  #Person2#: Where is your seat?
  #Person1#: It's 9 - A in the middle part, a window seat too.
  #Person2#: OK, you mean the vacant one on the left?
  #Person1#: Yes, it is. Thank you very much. Let me help you to carry your baggage there.
  #Person2#: No need. I have only this small handbag with me.
  #Person1#: Thanks. Have a nice trip.