Modal Auxiliary Verbs, Definition and Example Modal Verbs

Modal Auxiliary Verbs, Definition and Example Modal Verbs

Modal Auxiliary Verbs

In English, Auxiliary Verbs are seen as the building blocks of sentences. They are used to make the sentence negative, question it, or give the correct meaning in time. Auxiliary verbs are complementary to the verb in the sentence and have no meaning when used alone. There are some auxiliary verbs in English; am, is, are, have, has, do, does, was, were, did, and had. In addition, these verbs have a purpose. In order to indicate the time, an auxiliary verb is used to indicate the sequence of actions if one action happened before another, or to indicate an action that will happen in the future.

When the auxiliary verb makes the sentence negative, it is used after the subject and before the verb with the negative suffix ‘not’. In question sentences, the auxiliary verb is used at the beginning of the sentence, unlike other sentence structures.

The auxiliary verb is used to qualify the previous verb in order to avoid verb repetition instead of the main verb. The auxiliary verb is used when emphasizing the action in positive sentences. When stating that the action is passive, it is used together with the third form of the verb. Apart from the auxiliary verbs given above, there are also auxiliary verbs called Modals. These auxiliary verbs are used to add meanings such as need, necessity and probability to the sentence. Auxiliary verbs do not add their meanings to the verb, but Modals do add their meanings. Below are modal auxiliary verbs with sample sentences.


Can is used to describe whether something is possible or someone has the ability to do something. In addition, it can be used in cases such as requests, leave. Can is used when talking about probability, ability, and skills and also when making a request. For example:

  • Can I use your pen to complete my petition?
  • I can save a lot of money to buy a new home.
  • I can speak German well since we take German lessons at the university.
  • I cannot play football anymore because my leg was broken two years ago.
  • Can I have a glass of hot milk, please?
  • I can go to visit my mother this weekend.
  • Can we meet tomorrow night for a nice celebration?
  • I can spend more time with my cats as I am on vacation.
  • You can’t come here and talk sadly to us like that.
  • My emotions are constantly changing, I can start to cry suddenly while laughing too much.


Could is used as the past tense form of the modal word “can”. In questions and negatives could can be used with other verbs. Could be used for a weak probability present or future, but in this usage, the meaning is not past tense. ‘Could’ can be used to ask probability in questions, Could not means “impossible”. Also ‘Could’ can be used as a suggestion and offer. Besides, ‘Could you’ can be used in very polite request expressions. Could I / could we are very polite available for permissions and requests. For example:

  • I could write the numbers before I started school.
  • When my grandfather was young he could camp in the forests and catch fish.
  • I could play football before I got injured, but now I can’t.
  • They couldn’t pass last week’s exam, so they are very upset.
  • I could swim very well when I was little, but I have been afraid of the sea for a long time.


Should is used to indicate the recommendation, necessity, and what is right. Should can be used to express expectations and possible situations. For example:

  • You should start sports now, I think you have gained a lot of weight for two months.
  • I should travel for three hours by bus to visit my grandparents.
  • I should finish all the books in my library to get new books.
  • I should sleep early to get up early in the morning, otherwise, I will not be able to catch my exam.

Should is also used in question sentences.

  • Should we work hard to pass this exam?
  • Should I buy a car to go to work?

Should is used in sentences stating an obligation, giving ideas and advice.

  • You should stop smoking for your own and your family’s health.
  • To lose weight, you should exercise more often and stop eating fast food.


Would be used when asking “Who”, “What”, “Where”, “When”, “Why” and “How” questions. For example:

  • How would you solve this problem?
  • When would we have the courage to do this?

Would is used in request sentences.

  • Would you like some coffee?
  • Would you like some more milk for your coffee?

Would is used in conjecture sentences.

  • If I have a lot of money one day, I would like to help poor children.
  • If you come here one day, I would make you very happy.

Would is also used in question sentences.

  • Would you like to drink coke or wine with your meal?
  • Would you like to have fun with us tonight?


We use ‘must’ to describe the things we have to do. For example:

  • You are a child and you must sleep to grow up.
  • To avoid gaining weight, you must not eat fatty foods.
  • In order to learn to drive, I must first take a good course.
  • I must work hard to be successful like you.

Must is also used when giving people advice and suggestions about what they have to do.

  • You must wake up early in the morning for your health.
  • You must quit smoking to breathe cleaner.
  • You must clean your house for the guests to come.

When making negative sentences with Must, ‘must not or mustn’t’ is used when giving a strict ban on something and strongly negative advice.

  • You must not talk while the teacher is lecturing.
  • Since this is a green area, you must not step on the grass.

Question sentences with Must

  • Must I go to school today?
  • Must I know English to start the job?
  • Must you come this far to talk?