round on someone/something
phrasal verb with round verb [ T ] uk/raʊnd/ us/raʊnd/
突然回击;突然转身攻击;猛然反扑
to suddenly turn and attack someone or something
The fox rounded on its pursuers. 那只狐狸突然转身向追猎它的人扑来。
反击（批评）
to criticize someone who has criticized you
The mayor rounded on his critics with a very forceful speech. 市长突然发表了措词强硬的讲话，回击批评他的人。