Subject-auxiliary inversion

Subject-auxiliary inversion

In English, subject-auxiliary inversion (SAI) occurs when an auxiliary verb precedes a subject. This is an exception to the English word order convention of subjects preceding their corresponding verbs. See also Inversion (linguistics).

Circumstances for inversion

Subject-auxiliary inversion occurs in the following cases:

  • Questions where the answer is, generally, a "yes" or "no" response (as opposed to wh-questions); such questions are also known as polar questions. Yes-no questions must typically begin with an auxiliary verb.
Example #1: Did you finish your homework?
Example #2: Are you going to the store?
Example #3: Should I answer the phone?
  • Wh-questions with auxiliary verbs.
Example #1: When did you come back?
Example #2: What did he do with the car?
Unlike yes-no questions, wh-questions in which the matrix subject is questioned can be formed without inversion of an auxiliary verb.
Example: Who ate all the pies?
  • Declarative sentences with negative elements (i.e. never or not) are formed. See also Negative inversion.
Example #1: Never again will I watch that opera!
Example #2: Not since childhood did she eat cotton candy.
  • Declarative sentences with restrictive elements (i.e. only or so) are formed.
Example #1: Only on Fridays does he go to the bar.
Example #2: So hard did she work that she overslept the next day.
Example #3: So did I.

SAI also occurs in tag questions (He left, didn't he?), imperatives with overt subjects (Don't anybody move!), certain counterfactuals (Had the general not ordered the advance, the front wouldn't have fallen), and, optionally, in certain comparatives (She knows more languages than does her father) and related constructions.

SAI is usually thought to be a syntactic remnant in modern English of the more widespread verb-second (V2) phenomenon found in earlier stages of the language (and in all the other Germanic languages still), and still attested in archaic prose such as:

  • Example: Uneasy lies the head that wears a crown.