I'm pretty sure that "salir' in this context usually has the connotation of 'going out' to party, on a date, etc. "Leaving," as if one went away to school every Sunday night, is usually expressed by 'irse," If I ask "Podrias salir conmigo?" I am asking for a date. "Would you go out with me?"
One of the translations of "sale" offered by Duolingo is "leave". That introduces a lot of confusion if we use that translation and we're marked wrong for doing so.
"Salir" can mean leave, if you leave a specific place, for example if he left the room you could also say that he went out from the room "él salió del cuarto", it could also be used for for example a train leaving the station.
Does "todos" and "siempre" mean "always" in the same way? Are the perfectly exchangeable for the word "always"?
No, todos actually means all/every. In this case: all the sundays. But "you go out all sundays" is not what one would naturally say in English (but it is accepted by DL). So you should translate "I always go out" with "siempre", but you can translate "always on sunday" (literally: every sunday) with todos
I think 'You go out every sunday' is a more accurate translation, doesn't it?
I wouldn't agree to it being a more accurate translation. Your sentence conveys a similar meaning but I anticipate that it may have a very subtle difference in meaning. The answer we were given seems to be emphasing that you 'always go out' and your suggest emphasis on 'every' . IMO
Surprised one couldn't say "you always go out Sundays". With or without the "on" seem equally, gramatically correct in English.
Why isn't :...all THE Sundays" accepted? I'm not sure when to include the article when it is in the Spanish version and when to leave it out even if it is in the Spanish version.
"all the Sundays" would probably not be good English in most contexts-- although I can think of one where the "the" would be used.
In English, use "the" to refer to specific events, not to events in general as Spanish uses it.. for example, "the Sunday she left home.." refers to a specific Sunday. Whereas, "she goes out every Sunday" or " she goes out on Sundays would not have a "the." . These last two refer to "Sundays" in general.