The obligatory responsibility of the administrative law is mainly composed of statutory obligation, voluntary obligation, and promissory obligation.

行政法上的义务体系主要由法定义务、意定义务和承诺义务构成。

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The pairing is entirely voluntary, and there is no obligation to be a host or a guest.

这几个网站的功能都是让当地人和需要住宿的旅行者找到对方（配对）。 这个配对完全是自愿的，没有人被要求一定要接待或者成为客人。

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We're not looking for a mechanism in which we would have an obligation to reduce emissions of a legal form and the major emerging economies would have a voluntary program, "said Pershing."

潘兴说：“我们不想要一个我们有义务减排而主要新兴经济体可以自愿减排的机制。”

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" As ads become more voluntary, he says, "it puts a great obligation on the advertiser to be a part of the viewing experience and to add to the experience.

FORBES: ZAP!