Definition: In this task, you will be given a short story. One sentence from the story is chosen. Consider the events that happen before that sentence, or are likely to have happened before it. Does any of them directly cause it, or simply make it possible? You should write your answer in the form " A >causes/enables> B". Try to use phrases and sentences from the story to compose your answer when possible.
Input: story: Tom went to the store and bought a phone. He was very excited and began to run home. He ran too fast and dropped his phone. His phone screen had cracked. He picked the phone up and walked home sadly.
 selected sentence: His phone screen had cracked.

Tom drops his phone >Causes/Enables> Tom's phone cracks