Я был музыкантом. (следует поставить вопрос: кем (я был?)- это вопрос творительного падежа. а творительный падеж имеет окончание -ем, -ом(мужской род). Я - музыкант. Я кто? - вопрос именительного падежа. Я буду музыкантом. - "буду" всегда используется в будущем времени. например, я буду делать эту работу.

Past: Я был музыкантом Present: Я музыкант Future: Я буду музыкантом I don't know why, but we use an instrumental case in past and future...)

Hello! If u want to say "I was a musician" you should say "я был музыкантом " so, if u want to say who u were you should say "я был ...."for example: я был учеником, учителем..... if u want to say "I'll be a musician" u should say: "я буду музыкантом " so u say "я буду ... " for example я буду учителем, писателем... Good luck)

Thank you so much, patineuse - my grammar book tries to explain why the instrumental is used, but their explanation is not clear to me. Yours is. You explained in a very clear way to me. Thank you very much :-)

I know why. In the phrase like "Я музыкант" - "я" is always subject, музыкант - is a nominal predicate. It's a rule. It cannot be vice versa, in the contrary it should be written as "Музыкант - я" or better "Музыкант - это я." But in the past or future there is a verb. And if you write "Я был музыкант" you can see that both "Я" and "музыкант" are nominative. And it is difficult to understand which noun do you mean as a subject.If you stress by voice any noun, it becomes a subject and meaning will differ. Я был музыкант - it's me who was a musician. я был МУЗЫКАНТ means My profession was musician. (and now a I am a photographer). That's why we use Я был музыкантом in the meaning of "I was a musician". No double meaning. "Я" is subject. "Был музыкантом" Is a nominal predicate.