All credits to @Alex for inventing this type of puzzle with the original and the sequel.
- Guess an "R" - I can only be spelled right.
- Guess an "F" - Lots of me took place in the world wars.
- Guess an "L" - Most types of me are never seen
- Guess an "M" - I'm not a yes or a no.
- Guess an "N" - I am the always to some places on the moon.
Your answer could be in the form of:
The question was: ␣ p p l e
followed by explanation.