Concepts: classroom, smile, work
A: students smiling while working together because of the psychological safety in their classroom
Concepts: exit, passenger, station, train
A: passengers exit a train at the station .
Concepts: book, story, tell
A: book tells the moving and controversial story of elephants in a zoo during military conflict .
Concepts: depot, train, travel
A:
Trains are traveling down the train tracks at the depot.