Question

Объясните почему в словосочетаниях играть в дочки-матери в казаки-разбойники у существительных использована форма винительного падежа, совпадающая с именительным, а не с родительным.

Answer 1

Наличие предлога  диктует использование того или иного падежа.
Предлог -в- соответствует В.п., в Р.п. словосочетание звучит по-другому, напр.: играть без дочек-матерей в казакОВ-разбойникОВ

Answer 2

Explanation of the Use of Accusative Case in the Given Phrases

In the phrases "играть в дочки-матери" and "в казаки-разбойники," the accusative case is used, which coincides with the nominative case rather than the genitive case. This usage is due to the specific nature of these phrases in Russian grammar.

The accusative case is used to indicate the direct object of a verb, and it can also be used to indicate the destination of motion. In the given phrases, the preposition "в" (in) is used, which requires the following noun to be in the accusative case. However, in these specific idiomatic expressions, the accusative case coincides with the nominative case rather than the genitive case.

This phenomenon is a characteristic feature of certain idiomatic expressions in Russian, where the accusative case form is used in a way that does not follow the typical pattern of case usage. These expressions have become established in the language with specific grammatical forms that do not necessarily align with standard case usage.

This usage reflects the unique linguistic and cultural aspects of the Russian language, where idiomatic expressions often have their own grammatical rules and patterns that differ from standard usage.

In Summary: - The accusative case is used in the given phrases "играть в дочки-матери" and "в казаки-разбойники." - This usage coincides with the nominative case rather than the genitive case due to the idiomatic nature of these expressions in Russian grammar.