Answer:
I'm written with two letters, said with one and seen with two. What am I?
You turn me over after you have traveled far. What am I?
Forward I am heavy backward I am not. What am I?
I only exist when you are here. Where you never were I can never be.
What is light as a feather but even the strongest man cannot hold it for more than a few minutes?
The answer I give is yes, but what I mean is no. What was the question?