The verbs быть and стать with the Instrumental case
The verbs быть and стать in the past and future tenses are normally used with the Instrumental case. However, in everyday speech they can be used with the Nominative case (only adjectives and participles). When the quality is permanent, the Nominative case can be used, when it is something transient, the Instrumental case has to be used.
Его отец был француз (французом). His father was French. Permanent quality.
Он был слабым, но стал сильным. He was weak, but became strong. Temporal quality.
More questions like this one
- Russian Cases Test
- Instrumental Case
- What cases “Падежи” we use after the preposition “по”
- Russian Instrumental Case
- Russian cases: best resources
- What cases “Падежи” we use after the preposition “за”
- Russian cases, how to recognize them
- Russian translation of “вместо батареек”
- Verbs with Cases
- Case with the Preposition за