Is desu needed at the end of every single sentence? Also, can you add end particles at the end of every word/sentence?


When can _desu_ be omitted? Is it needed for every single sentence? Also, can
I add sentence ending particles to the end of any word? Such as, "学校ね？" as in
"school, right?" Thanks.

Edit: I'm still a bit confused on the topic. To my understanding, you need
something that acts like a verb at the end of a sentence like です/だ. I was
taught that です wasn't needed after an i-adjective, but was needed after an na-
adjective? Is that true, if so, why? Does an I-adjective act like a verb? This
also is a bit off topic, but when can you use だ instead of です and when can't
you? I've currently been living in Japan for a while now, and I still can't
get this basic concept down which is why it's worrying me. I've also read a
bit, but still struggle. Thanks for your help!




です is certainly not needed at the end of every single sentence. But if writing
or speaking in polite style ですます体 _desu masu tai_ or 丁寧語 _teineigo_ ,
sentences usually end in some form of です or ～ます.

Don't forget that there are other forms of です and ～ます including past
(でした、～ました), negatives ～ません, volitional (でしょう、～ましょう), etc.

The reason is of course that sentences usually end with a form of the copula,
or a 終止形 _shūshikei_ of a verb or adjectival verb ( _i_ -adjective). In 丁寧語
this is (some form of)

  * です as a copula,
  * ～ます as the ending for verbs, and
  * です again for adjectival verbs (this time not as copula, but merely as politeness marker).

* * *

In plain style, the situation cannot be summarized as neatly as ですます体 for
there are many more forms that could appear:

  * だ (or である) as copula
  * verb endings ～る、～く、～ぐ、～す、～つ、～ぬ、～ぶ、～む and their past forms
  * adjectival verb ending ～い and its past form ～かった

* * *

Sentence final particles can be added to any of the above endings, because
they are _sentences_. (In traditional grammar, a predicate — [noun phrase +
copula] or [verb] — is enough as a sentence.) However, 学校 by itself is _not_ a
complete sentence, so in traditional grammar 学校ね is _not_ allowed. (ね as
sentence final particle should attach to sentences.) Of course, rules are bent
in colloquial language, where 学校ね could be considered natural.

