Answer:
The more you add the less it weighs. What is it?
You may enter, but you may not come in. I have space, but no room, I have keys, but open no lock. What am I?
I start in little but I end in full you'll find me in half and complete.
I am the signature stroll of ducks and penguins
When you take away the whole from me there is always some left.
I flow from the Homerβs mouth when he sees doughnuts.