No. 13,056 in Russian
мамой
"Мамой" is the instrumental case of "мама," meaning "by/with (a) mom."
In a sentence
Я позавчера говорил с мамой по телефону.
The day before yesterday, I talked to mom on the phone.
In this sentence, "мамой" is used in the instrumental case, indicating the person (mom) involved in the action of speaking by means of an instrument or method.
Дома я всегда помогаю мамой заботиться о растениях.
At home, I always help mom take care of the plants.
Here, "мамой" is part of the instrumental construction used incorrectly; it should be "маме" to correct the sentence to proper grammar as "I always help mom," focusing on interactions centered around mom.
На празднике все были довольны моей мамой.
At the celebration, everyone was happy with my mom.
In this example, "мамой" again appears in the instrumental case, showing the relationship of mom to the situation or the people being satisfied.
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