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: Billy liked Christmas songs. But didn't know what a turtle dove was. He like turtle and knew they were green and had a shell. He also knew what a dove was, a type of bird. So he decided that 12 drummers drumming was a better part of the song.
 selected sentence: He like turtle and knew they were green and had a shell.

Billy learns what a turtle is >Causes/Enables> Billy knows what a turtle is