Inversion

A question is a common case of inversion
Has he packed his suitcase?
FORM:
BE /MODAL/ AUXILIARY VERB + SUBJECT + VERB

When they come at the beginning of a sentence.
Seldom
Rarely
Little
Barely
Nowhere (else)
Never (before)
Not (even)once
On no account
Only be
only in this way
Hardly (ever) … when
No sooner … than
Not only … but (also)
In no way
In / under no circumstances
Not since, etc
After the following expressions

Never have I eaten such an exotic dish.
Not only did the restaurant owner serve rotten tomatoes but were impolite to the costumers.
Seldom do I go out since my children were born. (but)
I seldom go out since my children were born.

With the expressions ONLY AFTER, ONLY BY, ONLY IF, ONLY WHEN, NOT UNTIL / TILL, the inversion is in the main clause.
Only if you have a nourishing diet will you have a healthy life.
Only after trying the recipe several times was she able to get the whipped cream

Were I you, I would tell the truth
(If I were you)
Had I been told, I would have asked before.
(If I had been told)
With conditional sentences

After verbs of movement or adverbial expressions of place when they come at the beginning of a sentence.
Outside the house was a big pine tree.
On the chair lay a cat
Here comes the bus
There she goes (not there goes she because she is a pronoun not a noun.)

With SO (+) / NEITHER / NOR (-) to express agreement
“I love turkey” - “ so do I”
“I have been to Brazil” - “so have I”
“I sent her a message” - “So did I”
AGREEING AND DISAGREEING (INVERSION)

“I can’t stand spiders” - “Neither can I”
“ I won’t do that” - “Nor will I”