You say is when describing a single object or person. Are is used for describing multiple objects or people. Ex: The apple is on the table.
Ex: The apples are on the table.
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".