answer: #Person2# helps #Person1# buy a white medium-size shirt.
documents: #Person1#: I want to buy a shirt.
  #Person2#: What color do you like?
  #Person1#: A white one, please.
  #Person2#: Maybe you could have a look at this one.
  #Person1#: What's the size?
  #Person2#: Large.
  #Person1#: I think a medium one will do.