Best riddles with simple answers

What does the following represent? N N N N N N N A A A A A A A C C C C C C C

Every time you stand up, you lose this. What is it?

Never ahead, ever behind, yet flying swiftly past; for a child, I last forever; for an adult, I'm gone too fast. What am I?

What you cannot hold it but it is yours?

What do you throw out when you want to use it, but take in when you don't want to use it?

What do you call an angry polar bear?

Think of a number. Double it. Add ten. Half it. Take away the number you started with. What is your number?

I go around all the places, cities, towns and villages, but never come inside. What am I?

It's red, blue, purple and green. No one can reach it, not even the queen.

What do you get when you cross a cow and a lawnmower?