answer: #Person2#'s girlfriend wants to learn the butterfly stroke so #Person1# suggests that she follow #Person1#. #Person2# thinks #Person1#'ll surely become a first-class swimmer.
documents: #Person1#: Does your girl friend like swimming? 
  #Person2#: Yes,she does. She is good at backstroke and free style. 
  #Person1#: Then you can help her with the breaststroke and sidestroke. 
  #Person2#: But she wants to learn the butterfly stroke 
  #Person1#: Really? Then just ask her to follow me. 
  #Person2#: I heard you are now practicing underwater swimming,aren't you? 
  #Person1#: Yes. But I still have some difficulties irt breathing. 
  #Person2#: Say, kid, keep on practicing, you're sure to be a first-class swimmer. 
  #Person1#: To tell you the truth,I have never thought of being a swimmer. I swim just for fun. 
  #Person2#: That's good.