Inversion of the verb before the subject is a common phenomenon in English sentences. The natural order of English sentences is (subject + verb + . . . .) but sometimes it becomes (verb + subject). Inversion is most common with question form of the sentences. However, there are few other circumstances where inversion of subject and verb occurs.
Inversion in questions:
Almost all forms of interrogative sentences (without subject questions and embedded questions) use inversion. These sentences always place the auxiliary verb before the subject.
- Is he going to the club?
- Did he go to the club?
- Where is the club?
- Who is that guy standing there? (No inversion for it is a subject question)
Inversion in other expressions:
Many other negative and affirmative sentences use inversion.
1. Affirmative and negative agreement: only after so, nor, neither but not in the cases of either and too.
- Alex went to the club, and so did
- Alex went to the club, and Jenny did too. (No inversion)
- Robert hasn’t reached yet, neither has
- Robert hasn’t reached yet; Robin hasn’t either. (No inversion)
- Russel is not a footballer, and nor is
2. Negative adverbial expressions at the beginning of the sentence.
- In no way should we accept their offer.
- Little did they know about me.
- Never has he felt so embarrassed.
- Seldom do they go
- Rarely do we see gypsies.
- Hardly ever do they talk to each other.
3. Beginning with only & not only.
- Only if they come would I go
- Only by researching can you solve this problem.
- Only after lunch can you play.
- Not only did they kill the adults, but they killed also the children.
4. Adverbials at the beginning of a sentence.
- Hardly had I reached there, he left.
- Seldom does the teacher finishes his class early.
- Rarely does Alex forget to do his
5. Adverbs of place (here & there) at the beginning of a sentence. This type of sentence requires the main verb (not the auxiliary verb) to come before the subject.
- There is a lady standing in front of the club.
- Here comes the king.
- Here is your home-made cola.
- There are so many people in that field.
6. Some prepositional phrases at the beginning of a sentence.
- Into the room came she when I was sleeping.
- Behind me cries a child.
- Over the table hangs a painting.
7. Conditionals without the conjunction
- Had he been there, he could have seen it.
- Were I the president, I could do the good things.
- Were he my brother, I would support him to reach his dreams.
- Should you go there, I will go with you.
Source: Learn Grammar