dialogue: #Person1#: Good afternoon.
  #Person2#: Good afternoon. Can I help you?
  #Person1#: I've got this important letter to send to Hainan. Can I send it by registered mail?
  #Person2#: Certainly.
  #Person1#: How much will I have to pay?
  #Person2#: Two yuan, please.
  #Person1#: Here are the letter and the money.
  #Person2#: Wait a moment. It seems that your letter is overweight. Let me weight it.
  #Person1#: Is it overweight?
  #Person2#: I'm afraid it is. So you will have to pay two yuan extra. The total charge is four yuan.
  #Person1#: All right. Here is the money.
  #Person2#: Here are the stamps and your receipt.
  #Person1#: What shall I do with the receipt?
  #Person2#: You can keep it until the addressee tells you that the letter has been delivered. It is the proof that you sent the letter if it fails to arrive.
  #Person1#: Thank you.
  #Person2#: Not at all.
summary: #Person2# helps #Person1# send an important letter to Hainan by registered email. #Person2# asks #Person1# to keep the receipt until the letter is delivered.
topic: send a letter