A GPL proponent might argue that a license for free software must be upgraded periodically since we cannot anticipate what new use models for free software might be developed that restrict freedom.

GPL 的鼓吹者也许会辩解说，“自由”软件的协议必须周期性的增加严苛的改进，因为我们不能预料到会产生什么样的限制他们所谓“自由”的使用模式。

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You may not offer or impose any terms on the Work that alter or restrict the terms of this License or the recipients' exercise of the rights granted hereunder.

您能就本著作提出或增加任何条款，而改变或限制本授权条款，或被授权人行使本授权条款之权。

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Although state medical boards regulate who can obtain a license to practice medicine, they don't restrict doctors from performing procedures outside of their training or specialty.

CNN: Plastic surgery: 'Wild West' of medicine

They would not be obliged to grant a license for all European countries but would remain free to restrict their licenses to certain territories and to establish contractual royalties.

UNESCO: MEDIA SERVICES

The abandonment of the notion that a government-issued medical license is any guarantee of quality deflates the arguments of those seeking to restrict entry into the practice of medicine.

FORBES: Sometimes The Best Medical Care Is Provided By Those Who Aren't M.D.s