6格和4格。

2017.04.15从同呼 Yes, this is one of grammar ways to show theme-rheme relations (already known/new information) in the sentence. In Russian, word order and noun cases (sometimes plural number) is used, while in English you use articles and word order.

oh I see
thank you for your help

Johny

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2017.04.15wusong As you wish

BTW, in modern russian internet-slang there exists a phrase "Убей себя об стену с разбега!" ("You must kill yourself by running-up and running into the wall!")

such a positive phrase! i love it

Johny

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2017.04.14从同呼 Johny,
1. I failed to see the wall (you had previously talked to me about)
2. стенЫ I didn't see a wall (any wall)
стЕны I didn't see walls/the walls

so, in this case the Accusative case is used to refer to particular nouns and the Genitive case is used to modify non-particular nouns, right?

Johny

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2017.04.14wusong Однако в 2 ещё важно, на какой букве стоит ударение в слове "стены".

Если "Я не увидел стены", то это означает "Я не увидел одной стены (одну стену)".

Если "Я не увидел стены", то это означает "Я не увидел много стен"

спасибо!
and kill me...