Translation:Marcus and Livia are coming from the city now.
They are opposites: preposition a/ab = (away) from, and governs nouns in the ablative case: ab urbe, from the city.
The preposition ad = to, towards; at (with 'non-motion' verbs), and governs nouns in the accusative case: ad urbem, towards the city.
Both preposition and noun-form have to change, when we distinguish between FROM the city and TO the city.
Ablative has MANY uses, aside from being the object of some very common prepositions.
All the "FROM" prepositions (ab/ā; ex/ē; dē) control ablative objects. "WITH" (cum) and "WITHOUT" (sine) control ablative objects. "ON BEHALF OF" (prō) is another that controls ablative.
There are many purely ablative constructions:
ablative alone, without a preposition, can mean BY MEANS OF or WITH X as an instrument (instrumental ablative): Mīles hostem gladiō necat , The soldier kills an enemy WITH A SWORD.
Ablative alone can express a point in time: Prīmā lūce necesse est surgere , It's necessary to rise at first light.
Ablative alone (also with prepositions) can express SEPARATION: Herculēs omnēs metū līberat . Hercules sets everyone free from fear.
Grammar books will probably list more than twenty different 'types' of ablative.
Thank you very much for the thorough answer! I think I'll have to move on to a serious textbook after Duolingo, but this is a great way to start. I have started memorizing declensions, but I was not learning the ablative case because I didn't think it was used much.
Separate question, in case you're someone who knows, are they planning to add to the Latin course on Duolingo?
Thank you, you're more than welcome! (It struck me as a really good question!)
I always recommend the beginning textbook by Frederic Wheelock--it's pretty comprehensive, and served me as a reference grammar in my undergraduate years.
One of the commonest prepositions that governs ablative case is dē in the meaning "about, concerning," and as such used in ancient book titles:
Cicero's Dē rē pūblicā , "About the Republic" (or "ON the republic")
Lucretius' Dē Rērum Natūrā , "Concerning the Nature of Things"
Cicero's Dē Natūrā Deōrum , "On the nature of the gods"
Cicero, again: Dē Senectūte , "On old age"
and lots more!
I don't know about the Duo course, except what I read in the comment pages--I think they've said they're planning to expand the course eventually, but that this all takes time, and that the recent virus complication has slowed the process even more...
Hi Suzanne, For some reason it's not letting me reply to your comment below (the reply option is not appearing and I'm on my laptop) so I'll reply here: Good to know about the textbook and that other useful ablative preposition. In fact I have read De Rerum Natura twice, and love it. I want to learn Latin to be able to read classics such as that in the original, and perhaps also some Roman history or other interesting documents. Plus everyone continued to write in Latin throughout the middle ages so it would make reading lots of medieval history better.
It's ex tempore, by the way: "from the occasion" (and not from an earlier time). An ex tempore speech was composed as it was delivered, not composed at a previous time, written down, and then delivered. As if you were calling it a "spontaneous" speech.
ex can have the meaning of "from the inside out," i.e., if you're in the house and you go out of it, that's ex .
Whereas ab is more general: "away from."
I guess users don't realize how we record the audio. We have to use the tool built into the incubator. We have to hit record and then hit the stop button. There is no way to clean up the audio. We cannot record with another program, clean it up, and then upload. That means you'll here us click the mouse.
That's the best we can do with the tools that we are given.