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: Ian wanted a pool. But he didn't know how to swim. So he decided to practice swimming at his friend's house. But he swam there so often that he didn't need his own pool. Ian was glad that he learned how to swim though.
 selected sentence: But he swam there so often that he didn't need his own pool.

Ian practices swimming at his friend's house >Causes/Enables> Ian doesn't need his own pool