Given the task definition and input, reply with output. 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: Mary has worked at a car dealership for two Year's without selling. Sentence2: Her boss tells her that she needs to sell a car soon. Sentence3: One day a couple comes into the dealership and asks to see a car. Sentence4: Mary sells them a very big, expensive car.
Mary's boss is happy with her sale.