i am planning a trip in cambridge i would like a train from london liverpool street on sunday
alright , how can i help you today ?
{'service': 'train', 'act': 'request', 'slot_name': 'leave', 'value': '?'} {'service': 'train', 'act': 'request', 'slot_name': 'arrive', 'value': '?'}
what time would you like to leave and and or arrive by ?