杨蕊吧的回答：

委托书 为了进一步发展国际教育文化交流，做好中美校际合作，特委托某某某代表我校与美国有关院校就共同合作友好学校事宜进行协商。校际合作确定后由校长签字生效。此委托书有效期2006年3月——6月。 Letter of Authorization In order to further the international education and culture exchanges and improve the Sino-US inter-college cooperation, Mr./Mrs., on behalf of our college,is authorized to negotiate with the US xx College on matters relating to friendly colleges in common cooperation. The cooperation between our colleges shall be valid upon signature of the Presidents of both party. This Letter of Authorization is valid from March to June of 2006.

孙建文的回答：

委托书 为了进一步发展国际教育文化交流，做好中美校际合作，特委托某某某代表我校与美国有关院校就共同合作友好学校事宜进行协商。校际合作确定后由校长签字生效。此委托书有效期2006年3月——6月。 Letter of Authorization In order to further the international education and culture exchanges and improve the Sino-US inter-college cooperation, Mr./Mrs., on behalf of our college,is authorized to negotiate with the US xx College on matters relating to friendly colleges in common cooperation. The cooperation between our colleges shall be valid upon signature of the Presidents of both party. This Letter of Authorization is valid from March to June of 2006.

lol代练的回答：

不建议签授权书。建议签订正规的英文合同，详细约定代理权限，授权地域和产品责任等问题。