“合法的”的英语可以翻译为：lawful，legal，legitimate，rightful，legit ...

既然出售香烟是合法的，那么禁止做香烟广告就是违宪的。Banning cigarette advertising would be unconstitutional, since selling cigarettes is legal.别担心，交易是完全合法的。Don't worry; the deal was completely above board.这笔生意看起来是合法的。The business seems legit...