answer: #Person2# tells #Person1# the seat isn't available and suggests #Person1# ask the conductor.
documents: #Person1#: May I sit here?
  #Person2#: I'm afraid this seat is taken.
  #Person1#: Oh, is it? Thank you anyway.
  #Person2#: You're welcome. If you ask the conductor when he comes by, he should help you find one.
  #Person1#: Thank you.