「だ」はいつか「が」のようにつかいます？ || だ sometimes used as a が? A couple of times I've heard だ being used mid-sentence, and this wasn't for things like connecting two sentences either like in the case of だから, it was more used in the context of "You won't take my sister away!" but the character at the time used a だ after "sister" when I was really expecting a が, or even an を, I can't remember the exact sentence. It's not the only time I've heard it like that either, although examples fail to come to mind.