The class I go to uses the «Minna no Nihongo» textbook, and according to it you can say the following in informal language:



(See book 1, lesson 20)

So I gathered, the copula can be omitted in adjective-like predicates. However, when I posted on Lang-8 applying the new-found knowledge, people corrected me:

ドイツはいちども行ったことがないから、ずっと行きたかった行きたかったんだ or 行きたかったです

Hence, the question: why だ/です is necessary here? What's the general rule?

  • 私はご飯を食べます also doesn't have a copula, but is standard (textbook) Japanese. I think you are confused about the term "copula". If you are asking whether every sentence needs an instance of だ or です, the above sentence already gives a counter example...
    – Earthliŋ
    Oct 5, 2013 at 22:09
  • 食べます being a full verb predicate doesn't need a copula. A copula, as I understand, is a verb to make predicates out of non-verbs like adjectives and nouns. E.g. Snow is white – "is white" is a predicate.
    – katspaugh
    Oct 5, 2013 at 22:24
  • 1
    I see. So-called i-adjectives are also called adjectival verbs (or verbal adjectives) sometimes, because they can be inflected and (contrary to na-adjectives, also called adj. nouns or nominal adj.) they don't need a copula...
    – Earthliŋ
    Oct 5, 2013 at 22:52
  • @Earthling, どうもありがとう、分かりました!
    – katspaugh
    Oct 5, 2013 at 23:04

1 Answer 1


I think the confusion arises because です can both replace だ as the copula (行きたかったんです), or simply mark politeness (行きたかったです).

The correction you received has little to do with a grammatical need for だ or です in a sentence, but rather the two improved versions sound more natural.

Grammatically speaking,


is perfectly fine.

You need a copula when you have a noun predicate. 行きたかったんだ needs だ because ん nominalizes the preceding phrase. 行きたかった alone doesn't need a copula, but may be marked with です for a more polite tone.

Your original sentence could be amended to

I had never been to Germany and had been longing to go...

in which case you don't need んだ or です.

  • Comprehended your answer after the second rereading. Thank you!
    – katspaugh
    Oct 5, 2013 at 22:39
  • What is the difference between the amended sentence and the OP's? All you have changed is from ない~ to なかった. In this case why don't you need the copula?
    – Nubcake
    Jul 20, 2015 at 13:42
  • 1
    @Nubcake grammatically you don't need です in both cases. I guess changing ない to past tense lends some explanatory tone to the sentence, so that the nominalizer ん (short for の) that was suggested on Lang-8 can be omitted (and with it, necessity for です).
    – katspaugh
    Jul 20, 2015 at 17:29
  • Now that I think about it , what is the difference between ~ことがない and ~ことがなかった ? Don't they both translate to ~ Have not done .. But the tense is different? I'm a little confused about this
    – Nubcake
    Jul 20, 2015 at 18:16

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