Answer:
I am there when you sit, but gone when you stand. What am I?
What happens once in June twice in August and never in May?
Lighter than feather and softer than silk, yet the strongest man in the world cannot hold me for more than a few minutes. What am I?
By Moon or by Sun I shall be found. Yet I am undone if there's no light around.
I must be broken before you can use me.
I have feet on my head