可逆 かぎゃく変化 へんかじゃなかったです
hikagyakuhenkajanakattadesu

Noun
Desu Copula

The polite, past negative form of 非可逆変化

1. It wasn't an irreversible change.; It hadn't been an irreversible change.

Past/Perfective
Negative
Polite
Casual Register