Teach Us, Teacher
N DA: an expression we use to explain something (Lesson 29)The basic form of N DA is NO DA. You say NO DA at the end of a sentence, when you want to explain what will happen, why or in what situation. In casual conversations, you use N DA. In a polite way, you say N DESU.
You cannot use the MASU form of verbs before NO DA. You have to use the plain form, such as the dictionary form or the TA form. Then, what will you say to explain "it will rain," if that kind of a cloud is seen? "It will rain" is AME GA FURIMASU. You change FURIMASU (to rain) to its dictionary form, FURU, and add N DA. So, you say AME GA FURU N DA. In a polite way, you say AME GA FURU N DESU.
NO DA becomes NANO DA, if nouns or NA adjectives come before NO DA. In such cases, N DA becomes NAN DA. So, if "work," SHIGOTO, is the reason, you say SHIGOTO NAN DA. In a polite way, you say SHIGOTO NAN DESU.