either you or one of your students

either you or one of your students
_________to attend the meeting that is due tomorrow.
为什么填is不是are呢?不是the one of+复数只有前面有the only谓语才用单数吗?

1.either...or...并列句子主语时,谓语动词的数必须采用就近原则,即和or后面的主语一致.
one of your students意思是“你学生中的一个/一个你的学生”,明显为单数,所以谓语动词用is而不用are.
2.至于楼主说的“不是the one of+复数只有前面有the only谓语才用单数吗?”,我估计你把定语从句的用法和该句用法混淆了.
1）He was one of the students who were late this morning.
他是今早迟到的学生中的一个.
其中关系代词who代指先行词the students,句意为“很多学生今早迟到,而他只是其中之一而已”.
2）He was the only one of the students who was late this morning.
他是学生中今早唯一一个迟到的.
其中关系代词who代指先行词the only one,句意为“所有的学生中,只有他一个人今早迟到”.
3.但是该题并非定语从句,句子主语的中心在one上,所以谓语动词必须用单数形式.