Verified answer

The plural of ora is ώρες (ores).That's the way we call it in our everyday speech.On the other hand, orai and Athinai are in katharevousa.They are not used anymore in our everyday speech.The combination of "a" and "i" (ai) in Greek is read like "a" in the word "say", while the simple "a" is read like "a" in the word "art".So as you can see, Athina and Athinai sound different. To sum up, the correct modern words are ores and Athina. The other two forms (orai , Athinai) are in katharevousa.