I'm compiling a chart for conjugating nouns, i-adjectives, and na-adjectives for a Japanese beginner, but I'm running into some difficulties in the negative tenses. I'd like this chart to be accurate in the sense of what sounds natural to Japanese speakers, not just what's "grammatically" correct.
Polite negative present tense: I know from posts like this that ~じゃないです is colloquially common (even if not as grammatically correct as ~ではありません), but does ~ではないです also sound natural? (Examples: 学生ではないです、きれいではないです). Or does this construction only sound natural as ~じゃないです?
Polite negative past tense: So ~じゃないです is OK (colloquially), but is ~じゃなかったです OK? What about ~ではなかったです? (Examples: 学生ではなかったです、赤くなかったです、きれいではなかったです). Or is negative past tense restricted to ~ではありませんでした? I'm not a native speaker but all these "sound" pretty OK to me, but I'm struggling to find examples online so maybe my hunch is wrong.
It might sound nitpicky asking separately for ~じゃ and ~では, since they're grammatically the same thing, but I want to confirm that they all sound natural so I don't accidentally suggest that a beginner go out and start saying things that sound "off".