On "A Dictionary of Basic Japanese Grammar", when a grammar pattern works with the informal form of a verb, they only talk about the positive present tense and the positive past tense. (At least until page 131, which is where I'm currently in). I think it's just the way this book works, but I'm not absolutely sure.
For example:
Could...
雪子さんとはデートしただけです。
...be...
雪子さんとはデートできないだけです。
?
Or could...
あの人はよく勉強するだけではなくよく遊びます。
...be...
あの人はあまり勉強しないだけではなくあまり遊びません。
?
By the way, when we use informal adjectives, could I write...
この家は大きくないだけです。
...or can't I use the negative form?
The same question for な-adjectives. Can I say:
このお菓子は色がきれいじゃないだけです。
?
Basically, my question is: whenever I see "Vinf" (informal verb) or "Adj (i) inf" (informal い-adjective) on this book, can I assume it's every informal form?
