"These cars are good."
Translation:Ĉi tiuj aŭtoj estas bonaj.
according to my notes¹:
tio that thing
tiu that person or specific thing
so, yes, "in general", -o refers to things - but if it's a specific thing, it gets the -u-ending.
¹I took a looong break from Duolingo, and am now trying to work my way back.
I am now studying this sentence and have the same question as thrustpork. I understand your the answer, phle70, but based on this the "this" and "these" words always refer to (a) specific thing(s). Please, somebody clarify when the "Ĉi tio(j)" formula can be used in Esperanto?
"Tio" and "ĉi tio" are used when the thing being referred to is unknown. For instance, you see a strange object in the distance, and you ask your friend, "What is that?" In Esperanto, that would be "Kio estas tio?" Your friend, who knows what it is, might answer, "Tio estas tre nova konstruaĵo" (That is a very new building). If the unkown thing was close by, you might ask, "What is this?" (Kio estas ĉi tio?) to which your friend would answer, "Ĉi tio estas tre nova konstruaĵo" (This is a very new building). Then later you visit a town for the first time, and you want to visit the museum, so you ask your friend, "Which building is the museum?" In that case, we know that the question refers to a building, so in Esperanto, it is "Kiu konstruaĵo estas la museo?" If your friend wants to answer "That building", in Esperanto, it is "Tiu konstruaĵo". If the building was very close by, your friend might say, "Ĉi tiu konstruaĵo" (This building).