answer: Mark is homesick and decides to write a letter to Mark's mom. #Person1# doesn't have any envelopes to borrow, but he tells Mark where to buy stamps.
documents: #Person1#: Are you all right, Mark? Is anything wrong?
  #Person2#: I'm so homesick, I could die. All this studying, all this pressure, I just can't stand it.
  #Person1#: It takes time to get used to all this.
  #Person2#: Yes. But, you know, I lost sleep last night.
  #Person1#: It seems like you've really got the blues. Have you heard from home recently?
  #Person2#: It's been almost a month since I got a letter from my mum. I'm going to write to her and explain the situation. By the way, do you have an envelope that I can borrow?
  #Person1#: Sorry, I don't have any. I hardly ever send any letters.
  #Person2#: The bookstore is closed today. Is there another place I can get some stamps?
  #Person1#: You can go to the post office on North Street to buy stamps.