answer: #Person2# tells #Person1# the time difference between Beijing and San Francisco.
documents: #Person1#: Excuse me. What's the time difference between Beijing and San Francisco?
  #Person2#: 16 hours. Beijing is 16 hours ahead.
  #Person1#: Are we losing or gaining a day on the way to America?
  #Person2#: We are gaining a day.
  #Person1#: So does it mean we're arriving on the same day?
  #Person2#: That's right.