They believe a public park should be free of charge.

他们认为城市公园不应该收费。

Mailing and delivery of publications for blind persons shall be free of charge.

盲人读物邮件免费寄递.

He asked me to give his pizza one more try, but this time it would be free of charge.

他问我给他一个比萨饼更尝试，而这次将是免费的。

After sales: give Security Technology Training Lecture free of charge once every quarter and be free to solve any technical problem on site for the client.

售后：每季度一次免费进行安全技术培训讲座，随时上门为客户解决技术问题。