Hmm, this particular phrase is a bit confusing. I wrote "the salad's plate" and it was marked incorrect- instead it says it should be "the plate of the salad." As an English speaker, I must point out that I would actually not say either of those phrases- they do not make sense (a salad cannot possess a plate). I would only either say "the salad plate" (which means "a plate to serve salad on") or "the plate of salad" (which means "salad that has been served on a plate"). Is "Το πιάτο της σαλάτας" the Greek equivalent of either of the last two phrases?