"I found a knife when I was cleaning your room."
Translation:Znalazłem nóż, gdy sprzątałem twój pokój.
It's a starred answer, it should have been accepted.
Unless perhaps you mixed masculine "znalazłem" and feminine "sprzątałam", such an answer wouldn't make sense.
Thanks, that clarifies things. Maybe I mixed up the genders, as you suggested.
Why not? It's 'your room', after all.
"sprzątać" takes Accusative, "pokój" is masculine inanimate, the right form is "twój".
Ok, but I was thinking that if it's the object of the sentence i.e. 'the room' which is being cleaned, and that then takes the Accusative, then surely the word 'your' must also take the Accusative, so I wrote 'twojego'.
The logic is correct, but "twojego" is not the only Accusative masculine option. It's used for animate nouns, which is not the case here.