Definition: In this task, you're given a four sentences of story written in natural language. Your job is to complete end part of the story by predicting appropriate last sentence which is coherent with the given sentences.
Input: Sentence1: Grady went tubing behind a boat. Sentence2: The boat went very fast. Sentence3: Grady was thrown off the tube. Sentence4: He did not remember how he got back into the boat.

Grady hit his head very hard.