A semi auxiliary verb is termed as a multi-word construction on the basis of an auxiliary verb. Semi auxiliary verb has some of the same grammatical characteristics as an auxiliary verb. It is also known as a semi-modal or a lexical auxiliary. A semi auxiliary verb is also known as marginal modal verbs. Like other proper modal verbs, semi auxiliary verbs are used with base form of verbs (infinitive) to form a unique meaning.

These are among the auxiliary verbs that are distinguished by many multi-word verbs. These are usually present in three-word combinations.

Few examples of semi-auxiliary verb are

  • be about to
  • be able to
  • be going to
  • be likely to
  • be supposed to
  • had better
  • have to
  • ought to
  • used to
  • would rather
  • get to
  • happen to
  • have to
  • mean to
  • seem to
  • tend to
  • turn out to
  • used to
  • be likely to

Some semi auxiliary verbs are followed by an infinitive and some are followed by zero infinitive.

Similar to other auxiliaries, semi auxiliaries usually occur before the main verbs.

The show is about to begin.

I am going to finish the rest of the assignment tomorrow.

I have to leave early for my chemistry class.

You are supposed to fill up the forms and submit by tomorrow.

I used to stay in that area.

Sometimes semi-auxiliaries are used in other context where they do not act as semi-auxiliaries. For example “I’m going to Australia.” In this example the combination is not considered as semi-auxiliary as it is not used with a main verb. In the example “going” is the main verb and not a semi-auxiliary.

The List of semi-modal verbs varies from one standard source to other. Few common examples of semi-modal verbs that are considered among the standard set are:

  • Dare
  • Need
  • Used to
  • Ought to

Dare and need are categorized as semi-modal because they can also behave as main verbs. Moreover, they are able to take nouns and infinitives as the object of the sentence and they are able to combine with person, tense, and number. Even though “Ought to” and “used to” are not able to act as main verbs but they are considered semi modal because these combinations are followed by infinitives. This is because actual modals can never be followed by infinitives therefore, “ought to” and “used to” is considered as semi-modals.

Few characteristics of Semi-Modal verbs

As these words act as semi-modal verbs they are used in combination with a main verb in a sentence in order to complete an entire verb expression.

They do not combine with third person singular subjects.

They can never have simple past tense form.

They cannot form infinitives or even past participles.

We will study the above examples of semi-auxiliary verbs and how they function as a semi-auxiliary.


Dare means to be brave, or rude enough to try something, reckless, etc. it acts as a semi-auxiliary verb. However, when it is used as modal verbs it does not combine with person or any tense. For example

If he dare question me again, I’ll make sure he repents for it.

As a semi-auxiliary verb the word “dare” forms a negative sentence with “not to”.  Rarely, the word is contracted as daren’t or is modified with the subject to create an interrogative sentence. Few examples are:

  • I dare not spread the matter any further.
  • How dare she behave so rudely with me?
  • Dare he cross the new laws passed by the government?
  • They daren’t give their professor a reason to angry.

The use of modal verb rare has become very less except in the sentence “How dare someone.”

Dare used as a main verb

It can act as an intransitive main verb that has same meaning as its modal version. When it acts as a main verb it is able to combine with person or tense. It can also be followed by a verb which is present in its base or infinitive form. In this case the use of “to” becomes optional.

  • I can’t believe he dared to speak against the professor.
  • No one dares to question the judge’s authority!

When dare functions as the main verb it must use the auxiliary verb “do” to form an interrogative sentence or to make the sentence negative. The main verb combines with tense person and number in such cases.

  • Dis they dare to complete the challenge?
  • He doesn’t dare to argue with his boss.

Dare can also convey the meaning “to challenge someone to perform something or complete something that needs courage, recklessness and boldness”. In such cases the word is combined with noun, pronoun, or infinitive as a direct object. However, in this case the word cannot be used modally.

For example:

  • I dare you to jump from a height of 5 metres.
  • I have never dared to bungee jump before.


Need is always used in negative sentences when the word act as a semi-auxiliary verb. It conveys the meaning to describe necessity or a lack of obligation. In such cases the word combines with the adverb “not” (usually in its contracted form needn’t) or it is paired with negative phrase or words like no one, nothing, never, etc. For example:

  • He needn’t have arrived so soon, I informed him the class will start late.
  • You needn’t worry about my health.
  • Nothing need change because we are shifting from one place to another.
  • No one need know about what happened.

It can also be used in interrogative statements by modifying the sentence and inverting the subject. For example:

  • Need we be worried?
  • Need I go to the shop tomorrow?

Nowadays, the modal use of need has become a rare case. The word is usually used in formal writing and speech.

Need used as a main verb

The word “need” is commonly used as a main verb. Therefore, it combines with person or tense to form third person singular or change its tense. Moreover, the word uses auxiliary to create negative statements and interrogative statements. “Need” while functioning as the main verb can be followed by noun phrases, nouns, infinitives, gerunds, etc.

  • The professor needs the assignment by tomorrow.
  • Does he need to know about the situation?
  • You have enough time to finish the exam, so you don’t need to hurry.
  • He needed some cash, so I helped him.

Used to

“Used to” is used for expressing a past habit, past fact that is no longer continuing, or a past condition. “Used to” is used as a semi auxiliary verb with the base form of the verb. For example:

  • I used to visit this restaurant regularly when I lived in Sydney.
  • She used to stay in Australia.
  • We use to play together in childhood.
  • This dress used to belong to my elder sister.

“Used to” is a very unique case where the interrogative and negative sentences are formed in same way in auxiliary and semi-auxiliary cases as that of main verbs present in past tense. This means “Did” is used for the question and did not for negative in all the cases.

  • Did you use to play chess?
  • I didn’t use to like pizza.
  • He didn’t used to run in the morning every day.

According to technical grammar the “–d” should be removed from the last example sentence when forming negative statements or questions because the auxiliary verb is present with the past tense “did.” However, “to” is immediately present after the word “use” so the “–d” is written even though the pronunciation is same and –d can be observed in many sentences. It is generally used in the English Language and can be written in both forms (with-d or without –d).

“Used to” used as a main verb.

One of the common mistakes is caused in the recognition of semi auxiliary verbs used in a sentence and when “used to” is used as the main verbs. Generally there are two main types of main verbs forms with used to

  • Be used to
  • Get used to

Be used to

“Be used to convey the meaning getting accustomed to something. It can be used as a main verb with noun, gerund of a verb, or a noun phrase. For example:

  • I am used to sleeping late at night.
  • Jennifer was used to the early morning practice by that point.

Negative sentence of the “be used to” combine not after the auxiliary verb “be.” This can also be used in its contracted form such as wasn’t, weren’t, isn’t, aren’t, etc. Interrogative sentence with “be used to” is formed by inverting the subject.

  • I am not used to staying in a polluted area.
  • She was used to so much stress and hard work.
  • Are you used to staying alone?

Get used to

In formal English “get used to” signify becoming used to something and also it is written as “become used to.” In this case the word “get” means become. However, in everyday writing and speeches “get used to” is acceptable and correct.

“Get used to” is used in present continuous tense. For example

  • I am getting used to the city life.
  • She is getting used to writing nowadays.

“Get used to” is used in past simple tense. Mostly it is used in negative sentences with the word “never.”

She never got used to staying at one place for a long time.

Most of the times we can notice the “Get used to” is used with the modal verbs such as will could, cannot, can’t, etc. Could is generally used to express hypothetical cases, will is used in reference to future tense (generally combined with never, and cannot is used for expressing the meaning “unable”).  For example:

Ana can’t get used to studying so many hours. She is often tired.

Anyone could get used to a luxury and extravagant lifestyle.

I will never get used to waking up early in the morning.

Ought to

“Ought to” is also categorised as a semi-modal or an semi-auxiliary verb as it ends with the word “to” and transforms verbs infinitive. It is often compared to should because it conveys the meaning that something is considered correct, necessary or preferable. Sometimes it also means, as something considered as probable, expected, or likely. Ought to can also be used while asking for something or offering suggestions about something.

With the increase in the rate of airfares, in-flight meals ought to be made complimentary and free. (Preference)

We ought to visit them tomorrow. (Probability and expectation)

I think we ought to change the direction. (Necessity)

You ought to see the beautiful places situated in India someday. (Recommendation)

The word “ought to” can be formed as a negative sentence by adding not in between ought and to. Sometimes the word is also contracted such as oughtn’t. To is usually omitted when ought to is combined with not. For example

You ought not to play outside for so long.

We oughtn’t walkout of the house; it is very stormy and unsafe.

Interrogative sentences are formed by inverting ought with the subject. However, this is quite uncommon. Again, “To” is usually omitted when “ought to” is combined with “not” in this form.

Ought we go out tonight to eat?

Oughtn’t Ana study for her upcoming semester examinations?

Ought they to be more stressed about the situation?

Ought not she to finish her homework first?

“Ought to” is very uncommon than “should” in modern English and it is rarely used in general speech, especially in American English.