倒装是英语语法中的一种常见现象，主要出现在疑问句、否定句、条件句和副词置于句首的情况下。倒装可以强化句子的语气和表达效果，提升语言表达能力。因此，理解并熟练掌握倒装结构的使用方法是非常重要的。
疑问句中的倒装
疑问句中的倒装结构是比较常见的，它可以强调句子的疑问性，让人更加关注问句的内容。例如：
- Have you finished your homework?
- Did you see the movie last night?
否定句中的倒装
否定句中的倒装通常是将否定词（如never、not等）放在句首，主语和谓语调换位置。这种倒装结构能够强调否定的意思，例如：
- Never have I seen such a beautiful sunset.
- Not only did she refuse my invitation, but she also insulted me.
条件句中的倒装
条件句中的倒装结构通常是将条件状语从句中的if省略，主语与谓语调换位置，例如：
- Had I known about the traffic jam, I would have left earlier.
- Were it not for your help, I would not have passed the exam.
副词置于句首的倒装
有些副词如never、seldom、rarely等置于句首时，也需要倒装结构，例如：
- Never have I been to such a beautiful place before.
- Seldom do we see such kindness in the world.
