answer: #Person1# wants to buy a book but #Person2# tells him it is sold out.
documents: #Person1#: Excuse me, do you have A tale of Two Cities? I'd like a copy of it. 
  #Person2#: Who is the author? 
  #Person1#: Charles Dickens. 
  #Person2#: Sorry, we 're sold out right now. Please come back next week. 
  #Person1#: Ok, Thanks.