Answer:
I am the book one can never finish reading
I can be long or short. I can be grown or bought. I can be painted or left bare. My tip can be round or square. (one word)
I run smoother than any rhyme I love to fall but cannot climb.
What can run but never walks licks but never talks has a bed but never sleeps has a mouth but never eats?
Flat as a leaf, round as a ring; have two eyes, can't see a thing. What am I?
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.