"Our professor spoke to us about paganism."
Translation:Ο καθηγητής μας μας μίλησε για τον παγανισμό.
The choice of the above only was marked incorrect. The second correct phrase which needed to be included was " ο καθηγητής μας μίλησε για τον παγανισμό" ? This was in a strengthen module.
That's because the original sentence was ο καθηγητής μας μίλησε για τον παγανισμό, but we can't change it, so we added Ο καθηγητής μας μας μίλησε για τον παγανισμό. And now both are best translations and can't remove the old one. We'll see what we can do about it... Thanks for pointing it out.