answer: #Person1# and #Person2# decide to send Mary a book as a birthday gift.
documents: #Person1#: Mary's birthday is coming. What shall we buy for her?
  #Person2#: Is a pen OK?
  #Person1#: Er... She has lots of pens. What about getting her a bicycle?
  #Person2#: Oh, no. We can't afford it. Let's get her a book. She loves reading very much.
  #Person1#: That's a good idea.