i need help booking a train to cambridge today .
{'service': 'train', 'act': 'request', 'slot_name': 'depart', 'value': '?'} {'service': 'train', 'act': 'request', 'slot_name': 'arrive', 'value': '?'} {'service': 'train', 'act': 'request', 'slot_name': 'leave', 'value': '?'}
there are many trains going to cambridge today . where are you leaving from and what time do you want to depart or arrive ?