Editorial Tip of the Week: The Auxiliary Verb

The auxiliary verb, or helping verb, is used with other verbs to form mood, voice, and tense in a work. The main ones are “can,” “do,” and “have.” “Can” uses only its stem form in the present indicative, like “I can,” “it can,” or “they can.” “Can” becomes “could” in the past indicative, such as “I could go for a walk.” Because “can” indicates an ability or permission, “can” is always followed by an explicit or implicit verb, such as “Can you carry the groceries?”

“Do” has two forms in the present indicative: “does” for third-person singular and “do” for all other persons. In the past indicative, the form changes to “did” for all persons while in the past participle, the form changes to “done.” “Do” is only used in the present and past indicative as an auxiliary verb, but can also act as a principle verb when referencing performance, like in “he does well in school” or “they do good work.”

In the present indicative, “have” has two forms: “has” and “have.” In the past indicative as well as the past principle, the form is “had.” As a helping verb, when the present or past indicative of “have” comes before the past participle of any verb, that verb’s present-perfect or past-perfect form is used, like with “I have looked everywhere.”

For more information about auxiliary verbs and a list of others besides “can,” “do,” and “have,” be sure to check out The Chicago Manual of Style at www.chicagomanualofstyle.org.