hello . i need a train ticket on a train going from cambridge to ely .
{'service': 'train', 'act': 'request', 'slot_name': 'leave', 'value': '?'} {'service': 'train', 'act': 'request', 'slot_name': 'day', 'value': '?'}
what day would you like to travel , and at what time do you want to leave ?