Почему так? Почему сослагательное наклонение в русском варианте? Ведь у меня же нет "would".
Да, ты прав. "Will have been" более конкретно чем "would have been." Значит нет прямого перевода "will have been." Просто "будет." Может быть "должно будет быть"? Или это "should be," только без будущего определения
No, it isn't wrong, but Duolingo sometimes has trouble with complex English tenses and participles.
I would say it is wrong. The sentence is not stressing completion, so using a perfect tense, in this case "will HAVE been" is incorrect.
So I found this image online with simple examples of all the verb tenses and how they would be translated into Russian: https://i.stack.imgur.com/ODpj5.jpg I feel like in both languages you need an additional clause or statement to justify the use of the future perfective. Theoretically it could translate as "К трем часам все будет уже подготовлено" with a perfective past passive participle and the addition of the word уже but again without adding something (like "by the time you get here), it sounds excessive. Additionally, "готов" is more of an undefined state of being (it is the state of being ready), which is why it would be more necessary to use a perfective verb or participle to demonstrate completed action (in my opinion).
Is there any semantic difference between the constructions к + dative and до + genitive?
That's an interesting question, technically they have no difference, but in everyday life they seem to have slightly different meanings. If a person says "я это сделаю до пятого ноября", that often means the process is already going and it will be often done even some days before the fifth of November. If somebody says "я это сделаю к пятому ноября", that rather means, that the person estimates time for the job and in that estimation it takes some amount of days/hours; now the person is busy with some other occupation, but closer to the fifth of November he is going to start doing that new task to complete it until the fifth of November. In other words, "к пятому ноября" often means "you'll get the result on the fifth of November, but don't bother me before that date", while "до пятого ноября" often means "the fifth of November is the highest estimation and the result will be obtained even sooner, so I'll call you when I finish the task". But still you won't get in trouble if you interchange those constructions, they are technically equal. :)
It's like the difference between "by three o'clock," (к трём часам) and "until three o'clock" (до трёх)
"Until" in this sentence sounds like it's going to be ready "until" 3, at which point it's going to stop being ready. I would say "до трех" here would be better translated as "before" (maybe at 1430 as opposed to 1500), whereas к implies that it could take the entire time up until 1500 for it to be prepared.
If it is a typo, yes. But it probably sees "there" as a wrong word, not a typo.