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

Question

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!

Answer 1

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).

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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

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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.

Answer 2

Semantically, です is like English "be" (or its inflected forms, "am", "are", "is", etc). Whenever you're saying sentences like "This is a book" or "I am a student" in polite Japanese, you'll be using です at the end of each sentence. But not all Japanese sentences need it, just as not all English sentences have "be". In addition, です is a polite form, which means it's commonly used in business settings, but you won't be using です often when you're talking to your family members or close friends. If you're a beginner who has learned only a few sentence patterns, just keep learning Japanese and you'll soon encounter many sentences that don't have です.

Grammatically speaking, it's true that ね can be added at the end of almost any sentence. But ね has its own meaning, and saying ね improperly will make your sentence sound very weird.

Answer 3

Edit: I'm speaking about the form of a noun directly followed by another particle. As for omission of です that ends a sentence, that can happen. Please look at answers by other users.

In standard Japanese, you can't omit da or desu, or it sounds like a slang or a dialect called feminine language.

Apart from that, the form of 学校ね？ itself can appear in standard Japanese too. This time, it's a combination with filler (or interjectional particle) ね instead of the sentence ending one, and it can be used when you add sentence fragments to the previous sentence, or when you repeat or confirm what you think you heard or the opponent meant in the moment. Incidentally, this filler ね can take です in no relation to verbs.