Good Riddles

Question: Cold and dark, I'm the same as my neighbor. Flatter than a pancake, faster than a panther. Lighter than a feather I still prevail, Yet a million mean trying to lift me would fail. Expanding and shrinking throughout the day, When heat is highest, underneath I lay. I leave in the darkness of the night, And don't come back if there's rain in sight. What am I?

Question: What's small like a mouse but protects like a lion?

Question: If there were ten fish in an enclosed tank, and four swam away, three died, and three drowned, how many fish would be left?

Question: I'm priceless, and cannot be bought, Some seek my purpose, Others destroy me, Those who steal me gain no more, I never last forever, but can a life-time. What am I?

Question: I'll amuse you for an entire evening, But you won't remember me. What am I?