A little help with んーです please
I'm going out of my mind trying to find the answer for this. I want to use a Noun with んーです which requires the use of the plain form.
雨だ －＞ 雨なんです <- following the rule to drop だ add な ＋ んです
雨だった ー＞ ？
How can I apply that rule to the second one (the plain past form)? Is it a different rule?
Thanks in advance.