The adjective unable that describes a noun as lacking power, skill, means, or opportunity to do something. Example sentences:
He was unable to finish the race.
I am unable to repair my own car.
Mom was unable to find her scissors.
They were unable to get away for the weekend.
Instead of using the word challenging you can use the word gifted, special, special gifted.
or
Will, when, why, it, can
I have a stomach ache.
Myself
mixture
are
used to be
is, it, in the past.
no "It" is not used instead of he and she...
Answer.
Use the word "how" when asking "in what manner". Use the word "why" when asking "for what reason".