A:Hello,Robert!
B:Hello,Mr,Brown.
A:May I ask some questions?
B:Sure.
A:Is your birthday in August?（具体到月用in）
B:Yes,it is
A:And when is your mother's birthday?
B:Her birthday is on December 8th (具体到某一天用on)
A:How/What about your father?
B:His birthday is the same day with my mother's
A:Really?It's so interesting
B:Yes,they are both 40 years old