As I go through the WK lessons, I typically try to read/parse as much of the example sentences as I can (absurd as they often are) as practice. I ran into this sentence fragment (from 過ごす vocab):
It translates to:
…so we had to spend the hot day without an air‐conditioner.
I understand everything up to the きゃならなかったんだ. My knowledge of grammar is still pretty rudimentary, so bear with me. I understood 過ごさなきゃ as being “must spend time on,” and I thought ならなかった was the negative past conjugation of 成る (with explanatory んだ appended). But when I put those together, I get “we did not become that we had to spend time…”, which is the opposite of the translated meaning. I appreciate any help figuring this out!