"不仅而且"后面的动词形式是 部分倒装。当"not only"放在句首时，"not only"后面的谓语动词需要使用部分倒装的形式，即助动词或情态动词放在主语之前。例如：

1. Not only he but also you are clever.

2. Not only the students but also their teacher is enjoying the party.

这种结构强调了主语"you"和"their teacher"，并且使句子更加流畅和强调。