uuunut7517-san, Kurokuma-san,
kon'nichiwa!
Thank you very much for the great help, Kurokuma-san
Yes; "nan" or "nani" can be integrated into "affirmative" or "negative" sentences.
Like Kurokuma-san explained, the word for "what" can be either "nan" or "nani" depending on
the next word (the word "nan/nani" modifies).
For example, if you know how to tell time, you'd be able to say "I'll come at 3 o'clock":
(watashi wa) 3ji ni kimasu.
Now, you're not sure what time you can come, then the word "nan" replace "3". Then add "wakarimasen"
(= I don't know) at the end of the sentence.
(watashi wa) nan ji ni kuru ka wakarimasen.
Hope this helps!
Natsuko (奈津子),
Team JapanesePod101.com