"She reads you a book."
Translation:Αυτή σας διαβάζει ένα βιβλίο.
There is nothing in this sentence to indicate that the 'you' is plural, therefore both singular and plural should be allowed
Both singular and plural are indeed accepted and if yours was not it's clearly a technical error and should be reported directly to Duolingo. The course team is not responsible for accepting answers nor is it able to alter the Duobot.
Please report it here https://support.duolingo.com/hc/en-us
Indication of the used pronoun:
Is "αυτή διαβάζει σ' εσένα ένα βιβλίο" an acceptable alternative? I gave this as my answer and it was marked incorrect. I know this version utilises the pronoun's strong form, but the Tips and Notes section (if my memory is correct) said this is an acceptable alternative; especially if one is being emphatic with the indirect object. If it's not, I'm fine with that; but it would be useful to know why for future reference!
That's a word for word translation and is not correct. I don't see it in the hints which our records show have been unchanged in two years. It's better to learn standard Greek expressions.
Technical error in the question , sou (singular 2d person) SHOULD be a correct answer to this question.....