Having completed the basic grammar lessons about past tense, which introduce the idea of conjugating the adjectives into past tense, I have a couple of questions:
1. Why or when would you choose to use past tense adjectives instead of past tense です?
E.g.
おもしろいでした
Vs
おもしろかったです
2. The lesson discussed a past tense for い adjectives, and for negated adjectives of either form, but not for な adjectives. Does that exist? And if so, what does it look like?
Apologies if this is covered in some future lesson I have not yet reached...
Depending on if you're dealing with な or い adjectives you will conjugate differently. Because in your example おもしろい is a い adjective you can't stick a でした at the end like that as if it was a な adjective. To conjugate past tense with い adjectives, you get rid of the final い and replace with かった.
おもしろいでした
おもしろかった
then you can stick a です at the end for formality.
The way you conjugate for な adjectives is pretty similar to those of nouns, past tense will just be だった/でした. E.g: しずかでした (な adjective) がくせいでした (noun)
Past negative can seem a bit more tricky, but it's not. You add じゃない at the end, and because じゃない acts like a い adjective because of that final い you conjugate it like an い adjective, so しずかじゃない → しずかじゃなかった
な adjectives have a difference to い adjectives, where な adjectives have a relationship with nouns. You can't change the spelling of the word itself. That's where the です rather becomes a necessity, and handy for that purpose. You use です to convey tense by default, really.
い adjectives however, have to be changed. You just change the い ending of that adjective and that's all you need, since that takes care of putting the tense in the adjective.
Putting an ending like です for い adjectives only affects the formality of the sentence, but grammatically has no effect. So there is no requisite. For either way and either type of adjective, there's different kinds of "です" to use, and they come with some degree of politeness they're used for, if they are even used at all.
Depending on if you're dealing with な or い adjectives you will conjugate differently. Because in your example おもしろい is a い adjective you can't stick a でした at the end like that as if it was a な adjective. To conjugate past tense with い adjectives, you get rid of the final い and replace with かった.
Ah, maybe that's the nuance I missed: so い adjectives always use the かったです form, and な adjectives always use the でした form? So you wouldn't ever use でした with an い adjective like in my first example, and there's no "past tense form" for な adjectives. Is that correct?
