Answer:
I have cities with no people, forests with no trees, and oceans with no water. What am I?
I am pronounced as one letter, written with three. I come in blue, black, brown, or grey. Reverse me and I read the same either way. What am I?
Never ahead, ever behind, yet flying swiftly past; for a child, I last forever; for an adult, I'm gone too fast. What am I?
I begin and have no end. Eventually I will be the end of all that has begun.
I stay where I am when I go off. What am I?
Though not a plant, has leaves. Though not a beast, has spine. Though many wouldn't need this thing, It's more valuable than wine.