Good Riddles

Question: I go up and I go down,
towards the sky and the ground.
I'm present and past tense too,
Let's go for a ride, me and you.

What am I?

Question: What flies when it's born, lies when it's alive, and runs when it's dead?

Question: If you have me, you want to share me. If you share me, you haven't got me. What am I?

Question: How do you fix a broken pizza?

Question: one day there were two cops, they got a call saying there was some kind of mystery so they went to the house were the mystery was at, the lady there said she could not figure out how many letters the special word was, later the cops went home knowing that they had done a good job. How many letters was the special word?