連用形 of 「だ」 - difference between 「だっ」「で」「に」


Out of the conjugations of だ, the 連用形 is what is confusing me.

I understand だ、だろ、な、なら fine, but I'm confused about だっ、で、に.

I think my question might be a bit too broad and that's because I really have
no clue what I'm supposed to figure out. I might have some understanding of
those uses when I see them in a sentence, but grouped in isolation like that,
I'm perplexed.

Could someone explain how they're used or what they mean?




Well, だった is simply the past tense form of だ.

きれい **だった** 。 It **was** pretty.

で can get a little bit more complicated when you start to describe all the
cases it can be used, but it's basically just the TE-form of だ. So, if you
wanted to combine two sentences, for example "I went to the store" and "I
bought some food", it would become "スーパーへ行って、食べ物を買いました。" You put the verb 行く
into TE-form, and add on the next sentence. So, if your first sentence ended
with だ, you would do the same thing.

僕は学生 **で** 、数学を勉強しています。 I **am** a student, **and** I am studying math.

Also, the negative form of だ technically uses the TE-form as well.

で+は+ない ＝＞ ではない ＝＞ じゃない

Or is also used in the word である. Which is basically another way of saying だ,
but that's another topic for another time.

As for に I think you're referring to something like きれいに or 静かに where these
words would normally be followed by な, correct? You can think of this as
simply turning the adjective into an adverb.

これは **静かな** 部屋ですね。 This **is** a **quiet** room.

この部屋では **静かに** して下さい。 Please **be quiet** in this room.

