Inversion means placing the auxiliary verb before the subject — the same word order as a question, but in a statement. It adds emphasis, formality, or dramatic effect. Common at C1+ level.
When a negative or restrictive adverb starts the clause, invert subject and auxiliary.
Never have I seen such a beautiful sunset.
Rarely does she complain about anything.
Seldom do we get the chance to relax.
No sooner had I arrived than it started raining.
Hardly had she sat down when the phone rang.
Not only did he apologise, but he also offered to pay.
Not only is she talented, but she's also hardworking.
Under no circumstances should you open this door.
On no account must passengers leave their bags unattended.
In no way does this reflect my opinion.
Only after reading the report did I understand the problem.
Only when she spoke did I realise who she was.
Only then did he appreciate what he had.
Little did they know what awaited them.
At no time were the children in danger.
Nowhere will you find a better deal.
Drop "if" and invert to make conditionals more formal.
Had I known, I would have helped. (= If I had known)
Had she arrived earlier, she would have caught the train.
Were I you, I'd accept the offer. (= If I were you)
Were she to resign, the team would collapse.
Should you need anything, don't hesitate to ask. (= If you should need)
Should the weather improve, we'll go out.
Young as he is, he's very mature. (= Although he's young)
Hard as she tried, she couldn't solve it.
Much as I like him, I disagree with his methods.
Here comes the bus. (NOT: Here it comes → no inversion with pronoun)
Down fell the rain.
On the table sat a mysterious letter.
| Trigger | Structure | Example |
|---|---|---|
| Never | Never + aux + S + V | Never have I been so happy. |
| No sooner...than | No sooner + had + S + PP + than | No sooner had we left than it rained. |
| Not only...but also | Not only + aux + S + V, but also | Not only did she sing, but she also danced. |
| Only after/when | Only + time + aux + S + V | Only after lunch did he call. |
| Had (3rd cond.) | Had + S + PP, S + would have | Had I known, I'd have stayed. |
| Were (2nd cond.) | Were + S + adj/to-inf, S + would | Were I richer, I'd travel more. |
| Should (1st cond.) | Should + S + V, imperative | Should you see him, tell him. |
| Adj + as | Adj + as + S + be | Tired as I was, I kept going. |
| Little | Little + aux + S + V | Little did they suspect. |
| Under no circumstances | Phrase + aux + S + V | Under no circumstances should you lie. |