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: Bert liked to barbecue outdoors. He took a plate full of steaks and opened up his grill. Bert didn't know that wasps had built a nest inside of the grill. Some wasps flew out, stung Bert, and he dropped his plate of steaks. Bert decided to keep his grill in the garage when he wasn't using it.
 selected sentence: Bert didn't know that wasps had built a nest inside of the grill.

Bert doesn't use his grill for a long time >Causes/Enables> Bert doesn't know wasps l=infest his grill