how long is not a complete sentence - "dura" is not accounted for in that translation.
I think "How long?" is perfectly acceptable. Given the context, "How long [does it last]?" is implied. Duolingo answers need not be complete sentences if past precedent is any indication...
This is incorrect. 'Quanto dura' = how long. 'How long is it?' should be: 'quanto dura è?' How long does it last? = Quanto tempo dura?
I tried "How long does he last?" (feeling cheeky)... but it didn't accept it. Is that really not an acceptable translation for some reason?
I tried "how long do you last?" with the same ... sentiment ... in mind. It was what the suggested translation of "dura"="(you/he/she/it) lasts" seemed to allow...
When I clicked on dura to give a hint it said (you) last. So i put how long do you last and was marked wrong