i am looking for a train to broxbourne .
user
what day would you like to travel on ?
assistant
i would like to leave on tuesday after 21:00 from cambridge . can you accommodate ?
user
yes , there are trains departing at 21:01 , 22:01 and 23:01 on tuesday . which time would like ?
assistant
2 tickets on the 21:01 , please . and can you give me the reference number once that s booked ?