"I eat on your plate."
Translation:Io mangio nel tuo piatto.
Thanks for posting! With the exception of singular family members, possessives always require an article. (Mia madre, mio zio, tuo padre BUT il mio piatto, il suo orso, i miei cani, le vostre scarpe...)
In this case, "nel" is already "in + il", so it does not require an additional article.
In the specific case, nel is a compound of in and il (nello is in+lo, nella in+la and so on) so "nel il" is repeating the article; in case you wonder, "nel" is the only form you can use, i.e. "in il" is wrong as well. The same applies to other prepositions: del (di+il), al (a+il), dal (da+il), sul (su+il), while col (con + il) is optional.
Am I the only person who finds this sentence, "I eat on your plate", which is accepted as a correct answer, strange? I mean strange to the point where I cannot envisage any time it would be used in English. Such a sentence makes very poor leaning material, even if it can illustrate some point about possessives and prepositions. I am left wondering whether "Io mangio nel tuo piatto" is similarly unlikely in Italian, or has some meaning that has been lost in translation