"Only I can do that!"
Translation:Nur mi povas fari tion!
Question gave me a sentence to write in Esperanto then marked me wrong and told me the correct answer was the English sentence that it asked me to translate.
If you experience such issues, I'd suggest taking a screenshot and raising it in the support forum. This forum is for language-related discussion; we can't help with how the app/site functions.
Manĝu terpomojn kaj feliĉiĝu!