When should I use な in "na-adjectives"?


I'm trying to understand something here, I have the following question I need
to answer:

> あなたの部屋はきれいですか？

to which I should answer something like

> ええ、きれい **な** です。

Why is the question does not contain the な?




Actually, your question is right and your answer is wrong.

You will only use な after a "na-adjective" if you're modifying a
noun/adjective with it, for instance:

> あなたの部屋はきれいですか (anata no heya wa kirei desu ka) Is your room beautiful?
>
> はい、きれいですよ (hai, kirei desu yo) Yep, it is beautiful.

**きれい is not modifying any noun, therefore there's no need for using な in
this.**

But if you wanted, you could word your answer like this:

> はい、きれいな部屋ですよ！ (hai, kirei na heya desu yo!) Yep, it's a beautiful room!

here we wanna state clearly that it is the room that has the quality of being
beautiful, in order to do that we, then, need to attach な after the adjective,
therefore:

**きれいな部屋 (na-adjective + na + noun)**




Actually, your question is right and your answer is wrong.

You will only use な after a "na-adjective" if you're modifying a
noun/adjective with it, for instance:

> あなたの部屋はきれいですか (anata no heya wa kirei desu ka) Is your room beautiful?
>
> はい、きれいですよ (hai, kirei desu yo) Yep, it is beautiful.

**きれい is not modifying any noun, therefore there's no need for using な in
this.**

But if you wanted, you could word your answer like this:

> はい、きれいな部屋ですよ！ (hai, kirei na heya desu yo!) Yep, it's a beautiful room!

here we wanna state clearly that it is the room that has the quality of being
beautiful, in order to do that we, then, need to attach な after the adjective,
therefore:

**きれいな部屋 (na-adjective + na + noun)**

