Answer:
What is it that given one, you'll have either two or none?
Where humans breathe liquid.
What is it that no man ever saw, which never was, but always will be?
Controlled by your hands and feet. It would be nothing without a street. What is it?
It covers you, you lose it every day and you'd die without it.
I am the fountain from which no one can drink. For many I am considered a necessary link. Like gold to all I am sought for, but my continued death brings wealth for all to want more.