"March is a month."
Translation:Ο Μάρτιος είναι ένας μήνας.
I must be missing something here...sometimes in sentences like this, it seems that you don't have to use the article. Other times, you must use the article otherwise it is marked incorrect. Can anyone shed some light on whether or not you need to use the article? I'm afraid I might be missing something.
Which article, the definite or the indefinite?
The definite article cannot be omitted.
The indefinite article is sometimes omitted. It could be in this case but it's not wrong to include it (again, in this case). Please read spdl's comment here https://forum.duolingo.com/comment/20814575 for the rule of thumb for omitting the indefinite article in Greek.