maggiesensei.com/2010/09/08/request-lesson-when-and-how-to-use-%e3%82%93n-%e3%81%ae%e3%81%a7%e3%81%99%e2%86%92%e3%82%93%e3%81%a7%e3%81%99%ef%bc%89/
Lesson on the casual particle ん and explanatory forms のです and んです, with comparisons to standard forms and numerous example sentences showing when to use each variant.
GrammarCasual speechJLPT N4AdjectivesJLPTConditionalsTutors and teachers