One is sitting down and will never get up.

The second eats as much as is given to him, yet is always hungry.

The third goes away and never returns.

What are they?

** The "first"  referred to in the riddle is a "Stove"

** The "second"  referred to in the riddle is a "Fire"

** The "third"  referred to in the riddle is a "Smoke"