answer: #Person1# helps #Person2# mail things to America by express air mail because #Person2# wants it to send as fast as possible.
documents: #Person1#: Would you like to mail it by air or sea?
  #Person2#: Hmm. . . How long will it take to mail things to the USA by air?
  #Person1#: About 10 days. You can send it express mail if you need it faster. It will only take three or four days.
  #Person2#: I want to send it by express mail. The faster, the better.
  #Person1#: OK, the postage is 275 yuan.
  #Person2#: Here you go.
  #Person1#: This is the receipt, please keep it. Have a good day.
  #Person2#: Thanks.