Questions & Answers about Окно было открыто, но в комнате всё равно душно.
Why is it окно было открыто instead of окно было открытое?
Открыто here is a short-form passive participle (краткое страдательное причастие) used as a predicate: (the window) was open.
Открытое would be the long-form participle/adjective (полная форма) and usually describes a noun inside a noun phrase, e.g. открытое окно = an open window (as a description, not the main predicate).
What exactly is было doing here? Can it be omitted?
Было is the past tense of быть (to be) and it marks past time for the state открыто.
In the present, Russian usually drops to be, so you’d commonly say: Окно открыто.
In the past, you typically keep it: Окно было открыто. In casual speech, it can be dropped sometimes if the past is clear from context, but that’s less neutral.
Why is открыто neuter? Is it agreeing with окно?
Yes. Окно is neuter singular, and short-form participles agree with the subject in gender/number:
- окно открыто (neuter)
- дверь открыта (feminine)
- балкон открыт (masculine)
- окна открыты (plural)