To whom do these glasses belong? Really? That needs to be added as a correct answer.
I second that though my version was marked as wrong was: to whom do these glasses belong
Very simply put: "di...chi" means "whose'. "Spectacles" are of course glasses but apparently it has not been included in the program.
More and more, English grammarians are giving up on the no-ending-a-sentence-with-a-preposition rule. In any event, twisting your sentence to accommodate the rule often leads to awkward phrasings and doesn't sound anything like how people actually speak.
I suppose that depends on who(m) you're talking to, or what you're talking about.
Di means from,so maybe it wasn't accepted because of that. But I put "Whom do these glasses belong to", which was also not accepted :-P
Di chi translates more to "of who" since the structure in italian to show ownership is "gli occhiali di lui" meaning "the glasses of him".
A similar example would be "la madre di Mario" meaning "the mother of Mario"
This being said, this is not an italian structure that can be translated word for word because they speak of ownership in a different way than in English.
Sure you can translate exactly, but it does'nt translate so smoothly.
Also, I think the main reason that the translation is marked as i correct is not for the grammer or the whose/to whom debate, but because of the world "belong" which is a verb that wasnt used in the original sentence. It may ultimately lead to the same meaning, but this sentence only uses the verb "essere" in the form of "è." If you use "belong" and try to translate back into italian you would see a different structure. Also, since you would be using "belong," the sentence would place more focus on the glasses than on who they belong to because the glasses are now "verbing" to another object
Why not "whose are those glasses"? Is there a difference between these and those?
As to whether there is a difference between these and those, yes, and the same is true in English. Questi (these) would apply to glasses that are nearby, maybe even in your hand. Quelli (those) would apply to glasses that are, say, across the room.
Because who's is an abbreviation of who is (who being a relative pronoun, and is the verb to be in third person singular) whereas whose is the possessive from of the pronoun who.
I also endorse saintsauveur's comment. I wrote spectacles and was marked incorrect. I'm going to report it.