In my opinion, the usage of だ is already correct in the following sentence. But someone in my other questions said it is incorrect.

For example,

  • 映画を見ることが好きだ女性は私の妹です。The woman who likes watching movies is my younger sister.

  • 使い方が便利だ電気機は何ですか。 What is the electric appliance that is handy to use?

For the sake of completeness and comparison, I provide relative clauses with a verb, i-adjective and noun as follows. I think they are also correct.

  • a verb: 映画を見ている女性が誰ですか。Who is the woman watching a movie?

  • i-adjective: 物価が安い町に住みたいです。I want to live in a town whose living cost is cheap.

  • noun: ジェットさんが２０歳だ映画を見ています。I am watching a movie in which Mr. Jet was 20 years old.

Must I change every だ to な in the given examples above? Please correct me if it is wrong.


Yes, you do have to change it.

It is ungrammatical for だ to appear at the end of a relative clause. If you need to have a (present-tense) copula at the end of a relative clause, it must be changed to either な or の. Which of these it changes to will depend on the noun attached to it---some turn into into な (like 好き or きれい), some turn it into の (like 普通 or 緑), and some can turn it into either な or の (like 特別).

この映画が好き → 好き映画(を見る)
この花は緑 → 緑花(を摘んだ)

The former group is where the term "na-adjective" comes from. Which group a given word falls into isn't really predictable. (See this question for more detail)

However, only だ must be changed in relative clauses. Past-tense だった can remain as it is in a relative clause.

この映画が好きだった → 好きだった映画(を見る)

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  • I chose this answer because you EXPLICITLY emphasized the exception in the present tense. To be fair, l'électeur is also good. – Friendly Ghost Aug 6 '15 at 4:33
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    +1, but I want to point out that this answer assumes that na-adjectives are a type of noun. That's fine, but it's not something everyone believes, so I want to point it out explicitly in case anyone is confused. – snailplane Aug 8 '15 at 21:52

You seem to be misunderstood about this and it is indeed a fairly common misconception.

「na-adjective + だ」

In na-adjectives, the 「～～だ」 form is the 終止形{しゅうしけい} (predicative form), meaning it is used to end a sentence. Thus, it cannot be used to end a relative clause in front of its final noun.

「na-adjective + な」

This is the 連体形{れんたいけい} (attributive form), meaning it is always followed by a noun. Thus, this is the form to use to end a relative clause since a relative clause will always end in a noun.

(Was it not you whom I explained this to only yesterday? With 「便利な」?)

Now, let us go over your sentences.


Incorrect. It is 「好きな」.


Incorrect. Again, な ＞ だ


Incorrect. Definitely, は ＞ が. A very common mistake among J-learners. Many use 「が」 as if it were the default subject marker, but it is not.




Incorrect. I wanna scream 「『だ』はsentence ender！」.

You could say 「ジェットさんが２０歳の時の映画を見ています。」

or 「ジェットさんが２０歳だった時の映画を見ています。」

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