のです, のだ, んです, んだ
Expression, の and ん add emphasis
the expectation is that ..., the reason is that ..., the fact is that ..., the explanation is that ..., it is that ...
Particle, used at sentence-end; indicates a question (sometimes rhetorical)
1. yes?, no?, isn't it?, is it?
after each alternative
2. or, whether or not
See 何か・1, after an interrogative
3. some- (e.g. something, someone)
indicates doubt, uncertainty, etc.; sometimes after other particles
4. hmm, huh
Prefix, See か弱い, emphatic prefix; usu. before an adjective