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: Tracy and Lee had a really big yard. It took Lee all day when he had to mow. It was hard work. For Lee's birthday Tracy surprised him with a riding mower. He was so happy!
 selected sentence: For Lee's birthday Tracy surprised him with a riding mower.

Tracy and Lee have a big yard >Causes/Enables> Tracy surprises Lee with a riding mower