[Amesaurus]

Well, think of something along the lines of

Sono inu wa kirei desu ne
That dog is pretty, isn't it?

I remember I had this in something I saved


In -na adjectives, the -na ending is used when the adjective modifies a noun, but not when it's used as a predicate. The past and negative cases are formed as they usually are in Japanese. Thus:

Kireina kimono (pretty kimono)
Kimono wa kirei desu ([your] kimono is pretty)
Kimono wa kirei dewa arimasen or
Kimono wa kirei ja nai desu ([your] kimono is not pretty)
Kimono wa kirei deshita ([your] kimono was pretty)
Kimono wa kirei dewa arimasendeshita or
Kimono wa kirei ja nakatta desu ([your] kimono was not pretty)