answer: #Person2# tells #Person1# the reason why the wedding is at 9 o'clock on Sept. 9th.
documents: #Person1#: When will the ceremony begin?
  #Person2#: The ceremony will begin at 9 0'clock. After the ceremony, there's a reception. By the way, do you know why they have chosen September 9th for their wedding ceremony?
  #Person1#: No idea.
  #Person2#: As in English, Chinese also has some lucky numbers. The number 9 stands for perpetuity in Chinese.