"Ένας σκύλος είναι απαραίτητος."

[DavidOdell1]

Μάλιστα!

[Snommelp]

Συμφωνώ

[Daniel147471]

Δίγλωσσος είναι απαραίτητος!

Duolingo is necessary!

[N.Feddes]

Could the people writing in Greek the discussion section please add an English translation to their comment? Helps the rest of us learn to give relevant commentary (in Greek) ;)

[charnfield]

Why not "ένα σκύλος"?

[Snommelp]

Σκύλος is grammatically masculine (as is pretty much anything that ends -ος), and so needs a masculine article.