When to omit だ when answering questions?


Maybe this is a stupid question, but in _Minna no Nihongo_ it says to omit だ
when giving a **positive answer** to a question.

> Question: こんばんひま？  
>  Answer: **うん** 、ひま。

But it is not explained if one can omit だ when answering this way:

**Example 1**

> Question: あなたはにほんじん？  
>  Answer: ううん、ちゅうごくじん (だ?)。

**Example 2**

> Question: あなたのしゅみはなに？  
>  Answer: にほんご (だ?)。

Do I have to put だ at the end of these two answers or should I omit it?




Grammatically in your cases using or omitting だ does not make any difference.

But Japanese speakers use specific forms in specific situations, and it
changes when the relationship between speakers changes.

In both example, the question sentence and ううん is quite casual, and sounds
like the speakers are female. Using a single だ for the end of a sentence is
strong and mostly used by male speakers, so I will omit it here. If you want
to use だ, adding another sentence ending particle after it will be more
natural. Ex. にほんごだよ




Grammatically in your cases using or omitting だ does not make any difference.

But Japanese speakers use specific forms in specific situations, and it
changes when the relationship between speakers changes.

In both example, the question sentence and ううん is quite casual, and sounds
like the speakers are female. Using a single だ for the end of a sentence is
strong and mostly used by male speakers, so I will omit it here. If you want
to use だ, adding another sentence ending particle after it will be more
natural. Ex. にほんごだよ

