generate response: could you tell me how long the trip is?. Intent: find_train. Slots: train-arriveby=12:30, train-day=friday, train-departure=london liverpool street, train-destination=cambridge
Response: TR0637 departs Cambridge at 09:39 on Friday and arrives at 11:07. The trip is approximately 88 minutes, barring any delays. There are few tickets left, would you like to book?