answer: #Person1# asks Stephen to work overtime, but Bob wanted to change shifts with Stephen. #Person1#'ll tell Bob and double Stephen's pay.
documents: #Person1#: Stephen, can you work overtime tonight?
  #Person2#: What's wrong? We have been working overtime recently.
  #Person1#: The holiday is coming so we need to finish our task.
  #Person2#: Must we finish our task before the holiday?
  #Person1#: Yes. The contract must be kept.
  #Person2#: OK. I know. But Bob wanted to change shifts with me tonight.
  #Person1#: Did he say why?
  #Person2#: He said he would celebrate his girlfriend's birthday.
  #Person1#: Don't worry. I will tell him about that.
  #Person2#: It is convenient for me to work overtime tonight.
  #Person1#: Thank you for that. And I will double your pay.