Logic Riddles

Question: What is the difference between a car and a bull?

Question: How do you make seven an even number?

Question: There were 2 trains heading the opposite directions on the same track.1 was going North, and one was going south, There was a 100m gap between them, avoiding the collision, 2 men saved the trains from colliding on time, Who were they and how did they save them?

Question: What goes on and on and has an 'i' in the middle?

Question: Insects have been disappearing for the past month. You are in a lab studying why and how this is happening, but the main door closes and you are locked inside. There are three doors in front of you that lead to freedom. Door 1: Hungry eating plants Door 2: Blood-thirsty vampires Door 3: Coldwater which you would get hypothermia quickly. Which door would you choose?