answer: #Person1# wants to mail the letter to the U.S and #Person2# tells her that it takes four or five days. Then #Person1# asks for a post office box.
documents: #Person1#: I want to mail this letter overseas.
  #Person2#: OK, Ma'am. I'll have to weigh it first. All right, it's not over- weight. That's 5.5 yuan for overseas mail.
  #Person1#: That's not expensive. How long does it take for a letter to get to the U. S.?
  #Person2#: It all depends. It usually takes four or five days.
  #Person1#: That's wonderful. It used to take more than a week when I was staying here six years ago. Well, I want to register it.
  #Person2#: All right. It's probably take a little longer to get there though.
  #Person1#: Yes, I know. Well, please let me have a post office box.
  #Person2#: That's OK. Fill out this form, please.
  #Person1#: How much is the rent per month?
  #Person2#: It's 100 yuan per year.
  #Person1#: Here is the form and money.
  #Person2#: OK. Here is the key for you. The number is on it. Any more requests?
  #Person1#: No, Thank you.