What's the point of Żaden if nie is already included? Duolingo translated this as "no" or "none" so it just seemed repetitive.. A little clarification would help - thanks!
If you just said 'Lekarz nie pracuje w niedzielę' that would mean 'The doctor doesn't work on Sunday'. To say that there does not exist a doctor who works on Sunday, you have to use 'żaden', which also requires that you negate the verb (note that double negatives work differently in Polish and in English).
"No doctor works on Sundays" --> Why is this wrong? If I said "on Sunday" wouldn't it mean just not on ONE Sunday, whereas on SUNDAYS would mean NO Sunday that exists?
Yes, it would. And actually that's what the Polish sentence says (most probably "the nearest Sunday" is implied).
General "on Sundays" = "w niedziele". The tail changes so much...
Well, as that's rather a nonsense sentence, it's hard to translate it. You can perhaps go with "Żaden doktor nie nie pracuje w niedzielę" which makes an equal amount of sense (zero), or perhaps a more logical "Żaden doktor nie odpoczywa w niedzielę" (No doctor rests on Sunday).
Yes, I'm basically asking how to say 'Every doctor works on a sunday' but I'm doing it in standard British English with the two negatives. It's not nonsense, it's how we speak! I'm wondering if this two negative form works in Polish?
"żadny" is not a word, although I understand why you would expect such a form. Well, no better explanation than "it just is that way".