Cecily G. answered 07/12/19
Trained in Grammar for Native Speakers and English Learners
Those are not adjectives above. Yes, you can add "s" in the case of "modals". In that case, we're referring to modal verbs as "modals" and so "a modal" becomes a noun, not an adjective. As far as "wounded" you can't add "s". We would say, "two hundred wounded". "Wounded" also in this case becomes a noun (meaning wounded persons/soldiers/etc).