臨界 りんかい前核 ぜんかく実験 じっけんじゃなかったです
rinkai zenkakujikkenjanakattadesu

Noun
Desu Copula

The polite, past negative form of 臨界前核実験

1. Wasn't a pre-critical nuclear experiment.

Past/Perfective
Negative
Polite
Casual Register