"only"引导的倒装句是 部分倒装。当"only"位于句首并修饰状语时，主句通常需要使用部分倒装的结构，即将助动词、情态动词或be动词置于主语之前。如果"only"后面跟的是从句，则从句本身不需要倒装，只需对主句进行部分倒装。

例如：

1. Only when it rains do you feel cool.

2. Only in this way can you make progress.

3. Only yesterday afternoon did I finish my experiment.

4. Only in a big city was it possible to buy a new wheelchair.