Question

分析一下这个which 引导的从句。主语是什么，those本应该是在send后吧

one is the immediate significance of solving the educational problem ,which will send back to school those who have been deprived of the right of education.

Answer 1

One主语 is 系动词谓语（the immediate significance表语 ）（ of solving the educational problem,定语）（ which will send back to school those 代词 who have been deprived of the right of education. 定语从句）
send those back to school , 但是后面who 句是those 的定语从句。就把those 后置了。
整个句子是定语从句中套了一个定语从句

Answer 2

主语就是which which应该是代one 有上文的话才能更好判断。
those是send宾语 一般是紧跟着send的 这里把back to school前置了。

Answer 3

主语就是Which本身，those...的确是为了句子结构平衡而被放在后面了