I’m working through the exercises in ch. 2 of Athenaze, where the implication from all the models seems to be that we would use articles in all the places where we would in English. For example, in ex. 2ζ-5:
Don’t sleep, man, but work in the field.
My translation of this would be:
Μὴ καθεύδε, άνθρωπε, ἀλλὰ πονε ἐν αγρῶ.
This is just my guess, going on the theory that articles weren’t very common in the ancient language and weren’t mandatory as often as in English. From what little I remember of my modern Greek, you also wouldn’t use the particle/interjection “ω” with the vocative either. (IIRC Athenaze says it’s not an article.) Would this really idiomatically be
Μὴ καθεύδε, ὦ άνθρωπε, ἀλλὰ πονε ἐν τῶ αγρῶ ?
For example, at the start of the Iliad, we have this:
Μῆνιν ἄειδε, θεά, Πηληϊάδεω Ἀχιλῆος οὐλομένην, ἣ μυρί.
No article on μῆνιν, and no ω on θεά.
This reminds me of traveling in Ecuador and telling someone “Tengo una novia.” Their response was “Una novia sola?”
On a side note, could you even say “πονε αγρῶ,” without the preposition, since the case implies something that would be done in the field?