别害怕督学（管理员）.他刀子嘴豆腐心,是一个好人.
His bark is worse than his bite:他急躁但无恶意 意译的话 刀子嘴 豆腐心 ,supervisor有监督人,管理人,检查员,督学,主管人,导师等的意思.根据你的需要选择吧.