RIDDLE

What is white when it's dirty and black when it's clean?

What has many keys but can't open any doors?

What has teeth but can't bite?

What is the end of everything?

They travel all over the world but end up in the corner, what are they?

David's father has three sons: Snap Crackle and ......??

What is more useful when it is broken?

What belongs to you, but other people use it more than you?

Can you guess what I am? Tall I am young. Short I am old. While with life I glow, wind is my foe. What am I?

The more you take, the more you leave behind. What am I?