だい

1. だい can also be used with declarative sentences for emphasis in boys' speech, as in (1)

(1)
• a. これは僕のだい。
• This is mine.
• b. 僕も行くんだい。
• I will go, too.

2. When だい is used with interrogative sentences, the sentences must be interrogative word questions. Thus, the following sentences are ungrammatical.

(2)
• a. *あの人は先生だい。
• Is that person a teacher?
• b. *村田さんも行くんだい。
• Is Mr. Murata going，too?

For yes-no questions, かい is used.

(⇨ かい)

3. Questions with だい, as in Key Sentence (A), and those with んだい, as in Key Sentence (B), correspond to questions without のです and those with のです in formal speech, respectively.

(⇨ のだ)

4. だい actually consists of the copula だ and the particle い. Thus, it can follow only な type adjective stems, nouns and noun equivalents. The following sentences are ungrammatical because だい follows a verb or an い type adjective.

(3)
• a. *だれが行くだい。
• Who is going?
• b. *どれがおもしろいだい。
• Which one is interesting?

5. In informal male speech, questions as in (3) are expressed as in (4)，with rising intonation.

(4)
• a. だれが行く？
• Who is going?
• b. どれがおもしろい？
• Which one is interesting?

6. The past form of だい is だったい, but it is not frequently used. The more frequently used past form of だい is だった with rising intonation, as seen in (5).

(5)
• a. 新しい仕事はどうだった？
• How was your new job?
• b. どこが静かだった？
• What place was quiet?

【Related Expression】

In informal speech, the question marker か (i.e., か2) is not usually used.

The following chart summarizes the endings for informal questions.

Sentence informalか is used in very informal speech or in vulgar speech. Female informal endings can also be used by male speakers.