Why the past in these sentences?

Question

I'm doing this exercise to write down from videos on the internet just to see how russian people speaks colloquially, and I got some question about it. I copied the whole speech, to preserve the context:

"как изучать русский язык: это правило будет сюрпризом для многих: не учите грамматику. это будет удивительно для вас, потому что с самого начала вы учили грамматику. вы постоянно писали что-то упражнения, сидели долго думали "какое там время?" и самая главная ошибка, которую вы допускали до сего момента, вы учили только грамматику. вы не уделяли должного вниманя разговорный речи.

1) why the verbs are at the past? 2) what is сего? 3) the strange thing is that которую is at the accusative case but not самая главная ошибка, I mean, all that part is the object of the sentence cause допускали is transitive verb, right? 4) question about listening: why I hear just "годня" or "час" and not "се" before them, when subtitles are сегодня or сейчас? thanks

Answer 1

A lot of questions in one Question :)

1) The verbs are in the past because the author is referring to your past activity - you used to learn grammar, you used to write exercises etc, "what about those times?" - i.e. how you will regret having spent so much time learning grammar. The Russian imperfective (past) does not have a literal translation to any particular English tense and has to be translated in context. It can take almost any English past form in the right context, but has the sense of habitual actions or actions being described in the moment. In this case the use is to describe habitual actions.

2) "Сего" is genitive of "сей" which is an old-fashioned word meaning "этот".

3) "Которую" is in accusative because it is governed by "допускали". "Ошибка" is in nominative because it is not governed by anything. But in the sentence "вы допустили большую ошибку" "ошибка" must be in accustive too.

4) It might be not very accurate pronunciation of the speaker or you have to train your listening skills :)

Answer 2

1. It's in the past, because it must be in the past. In English it would be something like "you were sitting, learning etc.".

2. Который takes a case suitable for the clause, not for the main sentence. That is, "ошибка, которая..." = "mistake which [does smth. itself]", but "ошибка, которую..." = "mistake which [is an object for some action]".

3. Сего is genitive of "сей" which is an old word for "this". Usually you may encounter this word only as a part of "сегодня" (i.e. "of this same day" = today) or "сейчас" (i.e. "this same hour" = now).

4. Normal pronounce should be kind of "сегодня"->"сиводня" and "сейчас"->"си(й)час", but sometimes people reduce these words into "сёдня" and "ща(с)". But I doubt you've really heard these variants.