Answer:
Use me to reward good behavior.
What is always coming but never arrives?
I am the reaction after enjoying soda.
I bring light to a dark world. In a current I travel and through tunnels I am hurled. Touch me and I'll kill you. What am I?
What is the difference between a poorly dressed man on a bike, and a well-dressed man on a unicycle?
No matter how little or how much you use me, you change me every month.