Riddles

1) There seems to be only one ordinary English
word that can be turned into another by replacing
a U with a V. Find it.

2) It runs and runs but can never flee.
It is often watched, yet never sees.
When long it brings boredom,
When short it brings fear.
What is it?

3) I start with the letter e,
I end with the letter e.
I contain only one letter,
Yet I am not the letter e!
What am I?

(Answers below)