階段 かいだん教室 きょうしつじゃありませんでした
kaidankyōshitsujārimasendeshita

Noun
Desu Copula

The polite, past negative form of 階段教室

1. It was not the staircase classroom.; It wasn't the staircase classroom.

Past/Perfective
Negative
Polite
Terminal Form