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: Jack got a pocket knife for his twelfth birthday. Sentence2: He wondered how sharp it was. Sentence3: He ran his thumb along the blade to test it. Sentence4: He accidentally sliced his thumb open.
After that he was always careful with knives.