generate response: I'm sorry, there's been a mistake. I need to book a train from cambridge to stansted airport. The train must leave after 10:15. I need four tickets.. Intent: book_train. Slots: train-bookpeople=4, train-day=saturday, train-departure=cambridge, train-destination=stansted airport, train-leaveat=10:15
Response: I have a 10:40 and every hour after that. Would you like me to book it?