Examples of Subject-Auxiliary Inversion
In English Subject-Auxiliary Inversion (also called Subject-Aux Inversion or SAI) is the movement of an auxiliary verb to sentence-initial position (preceding the subject) to form a question.
- a) Gretchen is singing the aria.
- b) Is Gretchen singing the aria?
Main verbs in English cannot undergo SAI, if we try to invert the main verb and the subject, we get a completely ungrammatical sentence in English (though the order is perfectly grammatical in some languages).
- a) Gretchen sings the aria.
- b) *Sings Gretchen the aria?
If a declarative sentenceOpens in new window contains an auxiliary verbOpens in new window such as have or be, a modal auxiliary Opens in new windowlike may or could, or the copular form of be, a yes/no question is created from the sentenceOpens in new window by applying the rule of Subject-Auxiliary Inversion, i.e., switching the position of the subject and the verbal element that follows it.
The sentences labeled “b” in 1) through 6) are yes/no questions that result from the application of subject-aux inversion to the declarative sentences labeled “a”.
Notice that in each case, the position of the verbal element that follows it have been reversed to create a question. The labels on the right describe the verb in boldface in each sentence.
1) Copular “be”
- a. He is a policeman.
- b. Is he a policeman?
2) Modal “could” + verb
- a. She could do it.
- b. Could she do it?
3) Aux “is” + verb (present participle)
- a. She is sleeping right now.
- b. Is she sleeping right now?
4) Aux “has” + verb (past participle)
- a. The boss has read the report.
- b. Has the boss read the report?
5) Modal “should” + aux “have” + verb (past participle)
- a. He should have read the report.
- b. Should he have read the report?
6) Modal “could” + aux “have” + aux “been” + verb (present participle)
- a. She could have been working then.
- b. Could she have been working then?
For declarative sentencesOpens in new window that do not have an auxiliary verbOpens in new window, a modalOpens in new window, or copular be, the rule of subject-aux inversion is not applied to form a yes/no question. Instead, an appropriate form of the auxiliary verb do is placed at the beginning of the sentence.
This process of adding do to a sentence is referred to as do insertion or do support. The auxiliary do allows the speaker to express tense differences, as 7a) and 7b) illustrate.
|7a) He runs every day.||Does he run every day?||simple present tense|
|7b) He ran every day.||Did he run every day?||simple past tense|
In British English, sentences with the main verb have (not the auxiliary verb have) also undergo subject-aux inversion to form yes/no questions, as shown in 8b). But in American English, do insertion is used instead, as shown in 8c). This is an important difference that learners of English should know.
- 8a) You have a pencil.
- 8b) Have you a pencil? → subject-aux inversion (British English)
- 8c) Do you have a pencil? → do insertion (American English)