Given scene/plot descriptions from movies or TV shows, and given a specific question about the scene, summarize the question into a title

Q: Doc Brown has got a time machine, why is he in a hurry in the end of Back to the Future part 1? Why doesn't he just give a parenting lesson to Marty?  A little more context: At the very end of part one, doc goes back to Marty to tell him about his son which is going to jail in the future and they need to stop that to happen. He is really in a hurry, but c'mon, you can wait a couple of days in the present then go back to the future at the very same moment he intended to go in first instance. He has plenty of time to achieve that!

A: Why is Doc Brown in a hurry in the end of Back to the Future part 1?
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Q: In The Commuter (2018), the train driver just died. Michael wants to detach the last rail car from a moving train. Sam, the conductor, is already on the last rail car where all the passengers have boarded. He says:    "Between the train and the people, I always knew it would be the  train"   and then jumps onto a moving train to get rid of a chain, which happens to be  stuck between two carts, aiding Michael, who had already been trying.  What is the meaning of Sam's words?

A: What is the meaning of Sam's words?
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Q: In The Count of Monte Cristo (2002), Fernand shot Mercedes and escaped on his horse but he stopped in mid-escape.    Then Edmond Dante arrivs and kills him.  Why did he stop himself from escaping?

A:
Why did Fernand stop escaping after he shot Mercedes?
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