In English we distinguish between direct and indirect (inverted) word order:
1) direct ― Subject ― Predicate ― Object (declarative sentences);
2) indirect (inversion of some parts for greater emphasis or with a special grammatical or communicative value).
Inversion can be of two types:
― full (when the predicate precedes the subject);
― partial (when only part of the predicate precedes the subject).
Inverted word order fulfils three following functions:
1. Grammatical
a) in questions:
Is he at home?
b) in exclamatory sentences which are negative in form but positive in meaning:
Doesn't she sing beautifully!
c) in conditional clauses introduced asyndetically:
Had he gone to her aid he would only have got himself caught.
d) in adverbial clauses of concession(if the predicative is a noun the article is omitted):
Child though he is, he is completely aware of the situation.
Tired though he was, he continued walking.
e) in the author's words in direct speech:
"Be quick!", said Pat.
But: “Be quick!”, he said (no inversion when the subject is a pronoun).
f) in stage directions:
Enter Napoleon.
Exit Lady Hummond.
2. Communicative (in order to provide the final position for the rheme, the most important communicative part — this is the so-called end-focus)
a) In sentences with the introductory there, here:
There were not too many people at the zoo.
b) In sentences beginning with adverbial modifiers, often protracted:
At a square table, on a stiff armchair of black wood sat Mr. Johnson.
c) In sentences beginning with so or neithe r (showing that the remark applies equally to someone or something else):
I like this melodical sound very much. — So do I.
But! We do not use inversion when so is used for emphatic confirmation.
You have stained your blouse with cherry. ― Oh, so I have.
3. Emphatic (to make any part of the sentence prominent by putting it in an unusual position)
In sentences beginning with:
a) negative words never, not,not only, not once, on no condition, on no account, no sooner, under no circumstances:
Never has she spoken with so much confidence.
b) semi-negative time adverbials: seldom, scarcely, hardly, rarely:
Hardly had we entered the house when the storm began.
c) words of restrictive meaning: well, many, little:
Little do they know about her.
Well do I remember her.
d) after only +time expression:
Only then did they realize their mistake.
Only when she came home did she realize that she had lost her purse.
But: Only Mary knows the answer (no inversion here).
e) words like so and such followed by that:
So dangerous did the weather become, that all the flights were cancelled.
Note: The inversion is partial here!
f) in sentences beginning with a predicative, adverbial modifier of manner or a postposition.
Tall and graceful was Jim.
Up flew the plane.
But: Up it flew.