Translation:I need to do exercises five and eight by tomorrow.
There should not be any difference. In standard Russian, unstressed "a" and "o" are pronounced the same - it's basically an а-like schwa sound (https://en.wikipedia.org/wiki/Schwa). There are, however, some local dialects that make a distinction between them and make an unstressed "о" sound о-like, but they just sound a bit funny to the majority of us native speakers.
I think so. It's wrong to use the singular "exercise" when there are two exercises in view.
Also saying "until" means something very different. The Russian sentence says I need to have them done by tomorrow - I do them once and it's over and done with. Your sentence means I need to be doing them until tomorrow - if I finish and it's not tomorrow yet, I need to start over and do them over again until it is tomorrow. In other words, your sentence is about working on a task for a set time period rather than completing the task.
No it is not bad english! The exercises are being referred to individually ( i.e. listed) so you can use "exercise" and not "exercises"
I guess this whole module needs to be UK language checked - gotten is archaic, classes are "at" school ( a school does not refer just to one building ) etc. The other modules seem fine and it is quite tiresome having to redo so many answers due to what I would see as bad grammar.
I think до завтра can be translated as either "before tomorrow" or "by tomorrow." Maybe I'm just a horrible procrastinator, but to me these aren't synonyms. The first means I have to have these done by midnight tonight. The second means there is some time tomorrow by which I must have them done (which could be as late as midnight tomorrow), so I can do them tomorrow if it's before that time. Does до завтра clearly mean one of these or the other, or does it depend on context?
Say instead of завтра (for which I don't think there's a к option) the sentence were about среда, would до среды vs к среде differ in meaning on this count?
As a native speaker of English (Irish style), "until tomorrow" would sound wrong. You use that with phrases such as waiting or lasting or enduring. It implies a duration of time rather than a point of time. So you could say "you have until tomorrow to do that" (duration) but on the other hand should say "do that by tomorrow" (deadline). In Ireland we would also say "for tomorrow" for a deadline, but Duo does not accept this.
I don't understand why people are saying “until tomorrow” and “by tomorrow” have wildly different meanings here. Every speaker I have ever met used both interchangeably in similar cases. To me, both should be accepted.
“Until tomorrow, this must be done.” “By tomorrow, this must be done.”
I've never seen any difference in those and never met anyone who does until I saw this Duolingo comment section. I must be unintelligent or just insane.
To me these mean very different things. Native of USA, New York.
If you say "I must do this UNTIL tomorrow" you mean you will start now and keep doing it and not stop until tomorrow comes. If you say "I must do this BY tomorrow" you can start and finish whenever you want, as long as you finish before tomorrow ends.
So you might say "I must keep guard until Sunday" (start now, don't stop before Sunday comes or we might get attacked!) or "I must clean the house by Sunday" (we have guests on Sunday, clean whenever you want but make sure to finish before they arrive).