什么时侯主语或谓语放在not only ---but also的前或后?

题目

什么时侯主语或谓语放在not only ---but also的前或后?
not only放在句首，后接句子时要用倒装结构。那为什么Not only you but also he is a student.
Not only he but you are a student.这两句话不用倒装？

答案