It's not clear how this makes any sense. Two people are in Rome and they say, "these olives are in Rome." So are the olives "from" Spain. Not buying it! ;-) The olives "IN" Rome would only make sense if the olives from Rome tasted especially good while eating them IN Rome. That is absurd.
I tried "These olives are Roman" because it seemed a more logical meaning to me, but it was marked wrong. Payson's explanation of the different words for Rome and Roman indicate why, just as some of the earlier discussions justify the sense of the model answer.
My thanks to everyone who takes the time to expand my knowledge, both linguistically and by coming up with ideas to show why Duo's sometimes strange sentences might actually make sense, especially since these justifications are often funny too.
I don't understand the use of "Romae" in this sentence. If it were expressing origin, wouldn't "hae olivae e/de Roma (Abl.) sunt", if it were an adjective such as "These are Roman olives", then: "Hae, olivae romanae sunt"? If it expresses location, then "Hae olivae in Roma (abl) sunt". The only case I can see for the genitive would be "hae olivae Romae", precluding the copula. Any thoughts?
Salve! I had never heard of the Latin locative, and it's super useful to know! Gratias tibi ago! Here is the full paragraph if anyone else runs into trouble:
Latin also had a Locative Case, but few of the forms are still used in Classical Latin. The locative case is used to indicate "place where" and is found primarily with the names of cities, towns and small islands. (Actually, these three places are all the same since the island has to be small enough to be named for the only city or town on it; if there are two towns, you much use in + Ablative. The forms for the Locative are the same as the genitive in the 1st and 2nd Declension Singular and the same as the Ablative in the 3rd Declension Singular. Towns (like Athens, Athenae) whose form is plural take their locative forms from the Ablative plural in all declensions. Other locative forms are: domi, humi, belli, militiae, and ruri.