Riddle #535

What needs an answer but doesn’t ask a question?

Some months have 30 days, and some months have 31 days. How many have 28?

The more you take away, the bigger I become. What am I?

What comes once in a minute, twice in a moment, but never in a thousand years?

I have 6 eggs, I broke 2 eggs, fried 2 eggs, and ate 2 eggs. How many eggs do I have left?

A man stands on one side of a river, his dog on the other. The man calls his dog, who immediately crosses the river without getting wet and without using a bridge or a boat. How did the dog do it?

A girl was ten on her last birthday, and will be twelve on her next birthday. How is this possible?

I get whiter the dirtier I get. What am I?

What country makes you shiver?

I build up castles. I tear down mountains. I make some men blind, I help others to see. What am I?

I am pronounced as a one letter alphabet. I am written with three letters. I am complete with just two letters. I am double. I am blue I am black I am brown I am gray I am yellow and I am green. I can read from both ends. I appear the same every way! What am I?