Answer:
What occurs four times in every week, twice in every month, only once in a year but never in a day?
Never ahead, ever behind, yet flying swiftly past; For a child I last forever, for adults I'm gone too fast.
What has keys but no locks, Space but no room, You can enter but you can’t exit.
In birth I spring forth, in life I unfold. In death I wilt and die, but rebirth restores all.
They can be long or short; they can be grown or bought; they can be painted or left bare; they can be round or square.
A leathery snake, with a stinging bite. I'll stay coiled up, unless I must fight.