"The man eats a lemon."
Translation:L'uomo mangia un limone.
Are you using an app? Many things can not be done with the Duoling app. I don't see how old a comment is on an app, for example.
More options are available if you use the Duolingo.com webpage, including the edit option. (On mobile devices, make sure you use the Request desktop site else it will likely redirect you to the app)