answer: #Person2# usually has a birthday party and sings 'Happy Birthday' at the party. #Person1# doesn't know when people began to sing the song, and #Person2# tells the story.
documents: #Person1#: When is your birthday?
  #Person2#: August 1st.
  #Person1#: Do you usually have a birthday party?
  #Person2#: Yes, we do. My parents prepare dinner for me.
  #Person1#: What would you do at the party?
  #Person2#: We sing ' Happy Birthday ' at the party and have birthday cakes.
  #Person1#: Do you know when people began to sing the song ' Happy Birthday '?
  #Person2#: Well, I don't know.
  #Person1#: Let me tell you the story. In 1892, Patty Smith Hill and Mildred Hill wrote a song called'Good Morning to you'. But later someone added the words'Happy Birthday'to their tune.
  #Person2#: So the'Happy Birthday'song has been popular since then?
  #Person1#: Yes, actually, the song has been sung since its publication in 1932. People all over the world have sung it in many different languages.