What is the grammatical mood of the verb 'пропой' in the sentence 'А ну-ка, песню нам пропой, весёлый ветер!'?

Explanation:

The sentence is: "А ну-ка, песню нам пропой, весёлый ветер!"

Let's identify the verb: пропой.

The phrase "А ну-ка" and the verb form "пропой" indicate a command or an exhortation.

In Russian grammar, the mood that expresses commands, requests, or wishes is called the imperative mood (повелительное наклонение).

The verb "пропой" is the singular, informal imperative form of the verb "пропеть" (to sing through, to finish singing).

Therefore, the grammatical mood of the verb 'пропой' in this sentence is the imperative mood.

Ответ: Повелительное наклонение