I am told to use propositional case with the names of the months to define time.
However, I am confused as I can't seem to find how. For example, how did Сентябрь becomes в Сентябре? Декабрь to в Декабре? Май to в Мае? Август to в Августе? Right?
May I know how to construct this? Or is it just simply change the endings into <<е>>?