I am Slovak (south neighbor of Poles with same language roots) and for me it is absolutely unnatural to put there an indefinite article. We don't have anything like that. The only similar situation is "some woman", but no "a woman". In other languages I don't have so big problem with this, but here... Even for the fifth try, i have wrote "woman speaks polish". I am damned.
I'm English and learning to get used to not using them. It's quite hard when you're used to them. 'Woman speaks Polish,' really doesn't work in English unfortunately - unless it's a news headline. At least you're not learning via French - they love all kinds of articles, everywhere. :-
Yeah, Duolingo really forces you to learn English grammar and spelling. This is more of a translation site than a speaking site. You don't really learn to speak languages, you learn to translate sentences correctly between languages. (Which of course helps on learning to speak the language too)
Why it can't be translated to "She speaks Polish"? I'm Brazillian and we don't use articles + substantives where you can just use a pronoun....
(Kidding.... I know Ona is the word for She... but I still hate the fact my brain is programmed to always use pronouns anywhere it can be used. ;--;)
Anywayz... what the hell is "Po"?