Answer:
What is in the middle of nowhere?
What is between heaven and earth?
We are two brothers on opposite sides of the road, but we never see each other. Who are we?
It goes up and down the stairs without moving.
Without this, H2O would just be 2O
It flows out of the soil, It burns you if it boils, And holds us in its coils, More valuable than gold, As black as it is old.