かわず 現象 げんしょうではありませんでした
ka wazuka genshōdewārimasendeshita

Noun
Desu Copula

The polite, past negative form of 蛙化現象

1. It was not the phenomenon of turning into a frog.; It wasn't the frogification phenomenon.

Past/Perfective
Negative
Polite
Formal Register