grammatical roles of だ and です
I'm trying to wrap my head around the grammatical roles of だ and です. So I came up with this "hypothesis" (tbh, it's probably too complicated for my current level of Japanese, but anyway). Since my thought process may fail at several points I split it into the following steps:
* Are だ and です used only to denote "X is Y" in sentences/clauses-of-compound-sentences that essentially look like "Xは/が...Yだ/です" ? (I understand that X in it may be merely implied.)
* Are Y and the consecutive だ/です inseparable in the sense they are always in the same 文節 (namely the last 文節 of the sentence/clause) ?
* Does that mean that we could think of だ/です as just another 助詞 modifying Y?----

When I put it this way, it may not be obvious where my question comes from. For a concrete example consider two sentences:
* 本を　読む。
* 本だ。
In the first one we can fill the space with almost arbitrary words or constructions. While in the second one, afaik, nothing can be put between 「本」 and 「だ」 except for a limited number of 助詞 directly modifying 「本」 (e.g. 「だけ」). Also in the second sentence we don't need anything like 「を」 or 「が」 — it's just「だ」 put "on top" of 「本」.
That's why I got the impression that the relationship between 「本」 and 「だ」 grammar-wise is different than the one between 「本」 and 「読む」, probably to the point of 「だ」 being just a suffix that turns 「本」 into a verb meaning "to be-a-book".

Question

grammatical roles of だ and です
I'm trying to wrap my head around the grammatical roles of だ and です. So I came up with this "hypothesis" (tbh, it's probably too complicated for my current level of Japanese, but anyway). Since my thought process may fail at several points I split it into the following steps:
* Are だ and です used only to denote "X is Y" in sentences/clauses-of-compound-sentences that essentially look like "Xは/が...Yだ/です" ? (I understand that X in it may be merely implied.)
* Are Y and the consecutive だ/です inseparable in the sense they are always in the same 文節 (namely the last 文節 of the sentence/clause) ?
* Does that mean that we could think of だ/です as just another 助詞 modifying Y?----

When I put it this way, it may not be obvious where my question comes from. For a concrete example consider two sentences:
* 本を　読む。
* 本だ。
In the first one we can fill the space with almost arbitrary words or constructions. While in the second one, afaik, nothing can be put between 「本」 and 「だ」 except for a limited number of 助詞 directly modifying 「本」 (e.g. 「だけ」). Also in the second sentence we don't need anything like 「を」 or 「が」 — it's just「だ」 put "on top" of 「本」.
That's why I got the impression that the relationship between 「本」 and 「だ」 grammar-wise is different than the one between 「本」 and 「読む」, probably to the point of 「だ」 being just a suffix that turns 「本」 into a verb meaning "to be-a-book".

Answer

”だ・です” are considered　「助動詞」.
there are  several ways that they are used such as the following
1: 彼が学生だ。（です）   shows  judgement or strong declaration.
2:それはおととしの夏休みです。（だ）  indicates something such as a time,place,object, etc.
3:こんな小さなことだけで諦めないんだ。（のだ）/ 勉強し始めたのは、言語学が好きなのです。（んだ・のだ・のです） explains reason/cause/basis 
4:もう中止です、中止です。 expresses determination with strong emotion and or declaration.

Answer

Im not entirely sure I understand your question. But だ/です are similar to the English words "is, am and are" I wouldn't say it modify's "Y" Can you eliminate だ/です ? In writing, no. But in really casual speech? Yea, you can, but it depends on what you're saying and how're saying it, eliminating them can sometimes make the sentence sound vague

hope that helps!

Answer

It's been pointed out that だ/です should be called 助動詞, not 助詞 since they can be conjugated.

So the question may be put this way: is it safe to assume that 助動詞 must always be attached to another word, namely to the one preceding it?

Answers · 6

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