Good Riddles

Question: Thirty white horses stand on a red hill,
First they champ,
Then they stamp,
Then they stand still.

What are they?

Question: I plow and plow, but never sow.

What am I?

Question: A man travels by wagon,
brings joy each evening,
but depression by the morning.

Who is he?

Question: I give advice to others,
yet I know nothing myself.
I am a hitchhiker destined to stay still.

Question: I have no wings but I fly,
I have no teeth but I bite.

What am I?