Good Riddles

Question: Six glasses are in a row. The first three are filled with milk and the last three are empty. By moving only one glass, can you arrange them so that the full and the empty glasses alternate?

Question: What's made of wood but can't be sawed?

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

Question: The more you work, the more I'll eat.You keep me full, I'll keep you neat. What am I?

Question: Two men, Watson and Holmes, are out in the extremely dry forest. They are completely surrounded by a large forest fire on one side and a dangerous cliff on the other. The wind is blowing the forest fire towards them and the cliff. The fire will reach them in about one day.

Holmes turns to Watson, "I have matches, berries, and enough water for a day. We aren't going to die." How can they avoid getting swallowed up by the forest fire?