Должно быть, она готовила обед, ког

Должно быть, она готовила обед, когда пришел брат.

Результаты (английский) 1:

She must have cooked lunch, when came the brother.

Результаты (английский) 2:

She must have been cooking dinner when he came to a brother.

Результаты (английский) 3:

Must be that she had prepared lunch, when he was his brother.