Answer:
What has to be broken before you can use it?
What object has keys that open no locks, space but no room, and you can enter but not go in?
You fill it and it empties, A metaphor for plenty, Depending on what half you see, It's either full or empty
I occur twice in eternity. And I'm always within sight.
No sooner spoken than broken. What is it?
Cycle Cycle Cycle.
Easy
Animal
Difficult
Food
Funny
Kids
Logic
What am I?