Auxiliary verb
An auxiliary verb is a helping verb placed in front of a main verb to build a tense, a voice, a question or a negative: the 'had' in 'had waited', the 'was' in 'was taken'.
She had waited. The main verb is waited. Had is there to help it, pushing the action further into the past. Auxiliary means helping, and auxiliaries are also called helping verbs.
The two kinds of auxiliary
Primary auxiliaries: be, have and do. They build tenses, the passive, questions and negatives.
- She had waited. Tense: the past perfect.
- The file was taken. Passive voice.
- Did she call? Question.
- She does not eat meat. Negative.
Modal auxiliaries: can, could, may, might, must, shall, should, will, would. They add possibility, ability, permission or obligation: you must go, it might rain. Close relatives such as ought to, have to and used to do similar work.
Auxiliaries can stack, and the order is fixed: modal, then have, then be, then the main verb. She might have been waiting has three auxiliaries and a main verb.
Auxiliary verbs in your prose
That stack is the pattern to watch. Every auxiliary you add puts more distance between the reader and the action, and in narrative prose that distance reads as hedging. She might have been waiting is five words where She waited is two, and only one of those sentences puts her in the room. It is the same effect described under filter words: the event reaches the reader through a layer of apparatus.
Two habits worth having.
- Flashbacks. Use had two or three times to step into the past, then move to the simple past. She had met him in Leeds. It had been raining. He held the door for her... A whole flashback in the past perfect is heavy going.
- Modals in narration. Treat any modal as a question worth asking. He would often go down to the harbour is right when the habit is the point; when it is not, he went down to the harbour is the scene.
Do not confuse an auxiliary with a linking verb: an auxiliary always has another verb after it. She was tired links; she was leaving helps.
Frequently asked questions
What is an auxiliary verb?
An auxiliary verb is a verb that helps another verb. It comes before the main verb and adds tense, voice, mood or a question or negative: had in 'she had left', did in 'did you call?', might in 'it might rain'.
What does auxiliary mean?
Auxiliary means helping or supporting. It comes from the Latin word for help, which is why auxiliary verbs are also called helping verbs.
What is the difference between an auxiliary verb and a modal verb?
Modal verbs are one kind of auxiliary. The primary auxiliaries are be, have and do, which build tenses, questions and the passive. The modals, such as can, might, must and would, add possibility, ability or obligation.
Can be, have and do be main verbs?
Yes. In 'she has a car' and 'he did the dishes', has and did are the main verbs. They are auxiliaries only when another verb follows, as in 'she has left' or 'did he go?'.