He thought the student was a brat the very first time he talked to him.
He thought the student was a nauty little boy when he talked to him for the first time.
brat を使って言えますよ！
ーHe thought the student was a brat the very first time he talked to him.
「彼はその生徒と始めて話した時、生意気な小僧だと思った」
brat の代わりに a naughty little boy を使っても言えます。
ーHe thought the student was a naughty little boy when he talked to him for the first time.
「彼はその生徒と始めて話した時、生意気な小僧だと思った」
ご参考まで！
カナダ 
