When is the suffix "-у" used for masculine nouns?
example:
мой мир= моему миру

Question

Answer

The suffix -y is used for the Dative case, which corresponds to English "to" in most cases. I gave the book TO MY BROTHER = я дал книгу моему брату. Some verbs require the dative, where English doesn't. For example, it is used with помочь 'to help' : I help MY BROTHER = я помогаю моему брату.

Answer

Strictly speaking this is not a 'suffix', this is an ending. Word endings are more volatile, unlike suffixes which do not change by case.

Answer

В примере это Дательный падеж, кому? чему?

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