同学你好，该知识点来自沪江网校《英语专业八级（TEM8）备考【随到随学班】》的课程，想要更系统的学习，欢迎进入课程学习。不仅可以和更多的同学一起学习，而且还有老师、助教随时的学习指导和知识点解答哦。

同学你好～

in behalf of 和on behalf of 都行，都是正确的。

behalf  
on behalf of sb also in behalf of sb
AmE a) instead of someone, or as their representative
　She asked the doctor to speak to her parents on her behalf.
　On behalf of everyone here, may I wish you a very happy retirement.
b) because of or for someone
　Oh, don't go to any trouble on my behalf.
【参考朗文~】  【其实还是 on 的版本更常见~】

祝学习进步～