You probably know that “each other” in Russian would be друг друга. What you might have missed is that друг друга should be declined, i.e. the last word should change its ending in different cases. Here is how to decline друг друга.
- Genitive case: Дети учатся друг у друга. Children learn from each other.
- Dative case: Мы доверяем друг другу. We trust each other.
- Accusative case: Они любят друг друга. They love each other.
- Instrumental case: Вы честны друг с другом. You are honest with each other.
- Prepositional case: Они говорят друг о друге. They speak about each other.
