絶縁 ぜつえん材料 ざいりょうではありませんでした
zetsuenzairyōdewārimasendeshita

Noun
Desu Copula

The polite, past negative form of 絶縁材料

1. Was not an insulating material.; Was not a thermal insulator.

Past/Perfective
Negative
Polite
Formal Register