What's the difference between tizenkét and tizenkettő?
What is the difference between plane and airplane? I used plane and my answer was rejected. I believe you should adjust it.
I can not adjust it but if you report it via "Report a problem", hopefully they will. Otherwise, both versions could be accepted. Hungarian can also choose to say "repülőgép" or just "repülő".
I think you will probably find that "Aeroplane" isn't accepted either, but as vvsey says we can only keep reporting these problems.
Rejecting "twelve aircraft" and saying it should be "twelve aircrafts"? Duolingo needs some English lessons!
A helicopter is an aircraft, but not an airplane.
And aeroplane sounds like an affectation, even in British English. But I may be wrong . . .
Is it possible that Twelve airplanes is flying above the city faulse