When to Invert the Subject and Verb:

1. Questions
2. Negatives
3. (Necessary) Prepositional Phrases of Place
4. Conditionals
5. Comparisons
   
   

1. Questions
   
   

   He is a doctor. He ate an apple.

   Is he a doctor? Did he eat an apple?

   (Direct inversion) (With “do”)

    

2. Negatives
   
   

   He is a doctor. He ate an apple.

   Not only is he a doctor, (but) he is also a millionaire. Not only did he eat an apple, (but) he also ate an orange.

    

3. Prepositional Phrases of Place (Necessary)
   
   

   On the table is a book.

   On the table (there) is a book.

   The prepositional phrase is necessary here, because without it, the sentence would be incomplete: (…is a book…is not a complete sentence.) Inversion is necessary.

   At the restaurant, the food was too spicy.

   (inversion is not necessary)

   Without the prepositional phrase, the sentence … the food was too spicy …is still complete.

   This structure is typically used with linking verbs (be, appear, seem, etc.) or words that function as linking verbs.

   In the doorway appeared two strangers. On the table lies my textbook. In the kitchen, he ate an apple.

   In the doorway were two strangers. On the table is my textbook. (Action verb: no inversion necessary.)