on invitation

基本解释

KING: It's nice of you for coming here to hunt on invitation, we especially select a docility horse for you highness.
国王：很高兴能见到邀请到你们来到这里狩猎，我们为贵国白雪公主特意挑选了一批温顺的马。
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On June 22, 2010, Chinese Foreign Minister Yang Jiechi had a phone conversation with UN Secretary-General Ban Ki-moon on invitation. The two sides exchanged views on the situation in Kyrgyzstan.
2010年6月22日，杨洁篪外长应约同联合国秘书长潘基文通电话，双方主要就吉尔吉斯斯坦局势交换意见。
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In judicial practice, opinions of jurisprudential scholar, which provided by legal experts through participating in argumentation of cases on invitation of judicature.
司法实践中，法学专家接受司法机关的邀请参与案件论证并出具专家意见，有利于案件的公正审理；

That could change on March 31, if Tehran accepts an invitation to join an international summit at The Hague.
But on his only mission to the region, earlier this month, he did not get an invitation to visit Pyongyang.
Israeli and Palestinian leaders have accepted an invitation from President Barack Obama for a three-way meeting Tuesday on the sidelines of the U.N.General Assembly in New York.

One interesting note, which may mean absolutely nothing: The artwork on the invitation closely resembles the drawings associated with its Google Now automated personal assistant on Android.
FORBES: New Phone? New Tablet? Google Sets Oct. 29 Android Event