You will be given a definition of a task first, then some input of the task.
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.

Sentence1: John had to shine six pair of boots. Sentence2: He got reprimanded by his supervisor for slacking off. Sentence3: John grumbled under his breath as he worked on the second pair. Sentence4: John spent three hours more, shining the boots.
Output:
John vowed never to disappoint his supervisor again.