"He is not necessarily an old person."
Translation:Él no es necesariamente un viejo.
@Katrin492472, notice that the word Él has an accent mark over the E. An accent is required on the É when it's being used as a pronoun for either a man or a boy, but not an object. So in the case of "Él no es necesariamente un viejo." The 'Él' literally translates to 'He.' Hope that helps.
08/04/18. “Él no es necesariamente una persona vieja” now accepted as an alternative correct answer. Thanks for listening Duolingo!
"Hi wordwing, You suggested 'Él no es necesariamente una persona vieja' as a translation for 'He is not necessarily an old person.' We now accept this translation. :) Thanks for the contribution, please keep it up! - Duolingo [04/02/18]"
The only reason that it might be marked wrong would be that DL wants students to recognize that when there is no antecedent then the subject pronoun should be used.
it seems it should be either, él no es necesariamente viejo OR él no es necesariamente una persona vieja, no? I had both marked wrong.
I believe that "un viejo" is translated literally as "an old one." I myself assume that "an old one" is euphemistic for "an elderly one" or "an elder." In accordance with your comment, a "lack of vigor" is often a sign of advanced age. Is this what you're talking about?
Él no es necesariamante viejo = He is not necessarily old.
Él no es necesariamente un viejo = He is not necessarily an old man/person.
In the first sentence, viejo is an adjective. In the second, it is a noun.
I put "Él no es necesariamente un persona viejo" and it was marked wrong. I can see that viejo does indicate an old man, but it would seem "un persona viejo" would still be correct unless it is NEVER allowed to mixed masculine and feminine in the same sentence, which I have never heard.
The word persona is always feminin, and hence you should always say una persona vieja, even about males.