004 which从句的逻辑 (3)

本次课内容

讲解下面这个难句：

There must be few questions on which responsible opinion is so utterly divided as on that of how much sleep we ought to have.

借此继续复习“介词+which+从句”的逻辑构造。

比如上句中的which前面的on来自哪里？

后边的as on怎么理解？

这里which引导的是什么从句？