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: Tony swung on the swing. He went really high. His glasses began to slide. They fell off. He picked them out.
 selected sentence: His glasses began to slide.

Tony swings on the swing >Causes/Enables> Tony's glasses begin to slide