To describe the exact tool you are using, or the specific person you are with, you need to put any attached adjectives and pronouns into the instrumental case.
Adjectives and Pronouns in the Instrumental
Modifiers must match the gender of the noun they belong to. Notice that masculine and neuter share the same endings.
| Gender | Adjective Endings | Pronoun Endings (этот, мой, такой) |
|---|---|---|
| Masculine & Neuter | -ым / -им | -им (e.g., этим, моим, таким) |
| Feminine | -ой / -ей | -ой / -ей (e.g., этой, моей, такой) |
You will also frequently use the reflexive possessive pronoun свой (one's own). It takes the same endings as мой and is used instead of "my", "your", or "his/her" when the owner of the object is the subject of the sentence.
| I am cutting this bread with my new knife. | Я режу этот хлеб своим новым ножом. |
| Why are you cutting the meat with such an old knife? | Почему ты режешь мясо таким старым ножом? |
Using Objects
The verb пользоваться (to use) directly requires the instrumental case for the object being used, even though there is no preposition.
| I often use this blue pen. | Я часто пользуюсь этой синей ручкой. |
| For work, one can use my old computer. | Для работы можно пользоваться моим старым компьютером. |
Doing Things Together
When you talk about who you spend time with, use the preposition с (with) followed by the instrumental case. Make sure to change any adjectives or pronouns describing the person to match.
| He is talking with his old friend. | Он разговаривает со своим старым другом. |
| She likes to walk with her younger sister. | Она любит гулять со своей младшей сестрой. |
| I often communicate with this smart person. | Я часто общаюсь с этим умным человеком. |
Hobbies and Interests
Just like пользоваться, the verbs интересоваться (to be interested in) and увлекаться (to be fond of / into) require their objects to be in the instrumental case with no preposition.
| My older son is interested in modern art. | Мой старший сын интересуется современным искусством. |
| Earlier I was interested in Russian history. | Раньше я интересовался русской историей. |
| My wife is into Russian music. | Моя жена увлекается русской музыкой. |
Contrasting Objects
To specify that you are using a different item, use the word другой (other / another). It acts exactly like a normal adjective, taking standard endings in the instrumental case.
| I usually use another spoon. | Я обычно пользуюсь другой ложкой. |
| We use this big spoon and that small fork. | Мы пользуемся этой большой ложкой и той маленькой вилкой. |