こう性能 せいのう爆弾 ばくだんじゃありませんでした
kōseino ubakudanjārimasendeshita

Noun
Desu Copula

The polite, past negative form of 高性能爆弾

1. Was not a high-performance bomb.; It wasn't a high-performance bomb.

Past/Perfective
Negative
Polite
Terminal Form