"You are sitting on top of a tree"
Translation:Mnakaa juu ya mti
There is no way to tell from the English sentence here whether the singular "you" or the plural "you" is wanted in Swahili. So unakaa (or umekaa) ... is as good a translation as mnakaa (or mmekaa). Confusion arises because Duo likes to invert question and answer as a way of coming up with a new question. Duo should have learned by now that this can lead to problems, and maybe take a proactive approach to fixing them.