How to use n desu
How to use the sentence pattern "n desu"?
Hi Cathy, I believed you are asking about the usage of the following expression:
Plain form のですか
Plain form のです
*Plain form means it can be plain form of verb, adjective and noun. But for plain form of both na-adjective and noun, instead of ending with だ (da), it need to change to な (na). Plain form 「だ」 -> Plain form 「な」.
In general, while in conversation the above sentence pattern will change to:
Plain form んです
That means when talking, native Japanese normally use 「～んです」 instead of 「～のです」.
This sentence pattern is used when the speaker explains to the listener the reason for his own words and deeds, while an interrogative sentence in this form is used when the speaker is asking for an explanation of what the listener has done.
anata wa bi-ru wo nomanai n desu ka
Meaning: Don't you drink beer?
ee, kirai na n desu
Meaning: No, I don't like it.
To use this sentence pattern "n desu", something should be obvious, something you have seen or heard. For the above example, it's obvious that the speaker noticed that the listener is not drinking beer and ask the question. And this sentence pattern always shows the speaker's curiosity or interest in the question.
Actually it's not a mistake if you omit ん (n) or の (no) in the above case. But it's just not natural for native Japanese.
Thanks for asking this question. I will probably explain it in more details in one of the intermediate lesson I will be doing.
Refer to this page for Japanese plain form.
Intermediate lesson 3: Japanese Sentence no desu.
Hope this helps,