Task: Story Composition
Input (English): Premise: Ben put his running shoes on. 
 Initial Context: He ran out of the door in a hurry. 
 Original Ending: He tripped on the top step. He barely stopped himself from falling down the stairs. He slowed his running pace. 
 Counterfactual Context: He ran on the treadmill in a hurry.
Output (English): He tripped on his shoelace. He barely stopped himself from falling off the treadmill. He slowed his running pace.