The 'ability' group
These nouns refer to abilities.
His eyesight is fine.
Bill tested my mettle more severely than any other suicidal client I have had.
I did everything in my power to make sure Russell would keep loving me.
Ability 1, inability, and incapacity are always followed by a to-infinitive clause.
ability accomplishments artistry capability capacity energy (usu plural) eyesight faculties hearing inability incapacity mettle potential power reach reactions sight skill touch
People also vary in their ability to communicate their needs and demands to others.