I'm not sure I follow. This sentence could translate to "are you smiling?" or "do you smile?"
How could you tell the difference when something is translated whether it becomes "det" "Dere" or "du" because I have gotten questions about that wrong.
"det" means "it", "dere" is the plural form of "you" (you all), and "du" is the singular form of "you".
So, I just got this one, gave the correct answer (minus the question mark), but was marked wrong. Does duo now recognize punctuation?
No, Duo ignores punctuation - either there was another mistake or it was a bug