The normal English order of subject-verb-completer is disturbed only occasionally but under several circumstances. Burchfield* lists about ten situations in which the subject will come after the verb. The most important of these are as follows (subjects in blue):

1. In questions (routinely): "Have you eaten breakfast yet?" "Are you ready?"
   
   
2. In expletive constructions: "There were four basic causes of the Civil War." "Here is the book."
   
   
3. In attributing speech (occasionally, but optionally): "'Help me!' cried Farmer Brown."
   
   
4. To give prominence or focus to a particular word or phrase by putting the predicate in the initial position: "Even more important is the chapter dealing with ordnance."
   
   
5. When a sentence begins with an adverb or an adverbial phrase or clause: "Seldom has so much been owed by so many to so few."
   
   
6. In negative constructions: "I don't believe a word she says, nor does my brother. Come to think of it, neither does her father."
   
   
7. After so: "I believe her; so does my brother."
   
   
8. For emphasis and literary effect: "Into the jaws of Death, / Into the mouth of Hell / Rode the six hundred."**

There are other uses of inversion, but most of those result in a strained or literary effect.