勉強べんきょう熱心ねっしんじゃなかったです
benkyō nesshinjanakattadesu

Desu Copula
na-Adjective

The polite, past negative form of 勉強熱心

1. Wasn't diligent.; Wasn't enthusiastic about studying.; Wasn't keen on learning.

Past/Perfective
Negative
Polite
Casual Register