Uses of Modal and Special Modal Auxiliaries

Understanding auxiliary and modal verbs is essential for effective communication in English. This guide simplifies these concepts to help students and non-native English speakers learn them easily.

What Are Auxiliary Verbs?

Auxiliary verbs, also known as helping verbs, work alongside main verbs to give additional meaning to a sentence. They help form tenses, moods, and voices, making sentences more meaningful and grammatically correct.

Definition: 

An auxiliary verb is “a verb such as be, do, and have used with main verbs to show tense, and to form questions and negatives” (Oxford Learner’s Dictionary).

Common Auxiliary Verbs:

• • Be: am, is, are, was, were
  • Have: have, has, had
  • Do: do, does, did

Examples:

1. “I am reading a book.” (Present continuous)

2. “She has completed her homework.” (Present perfect)

3. “Do you like ice cream?” (Question formation)

What Are Modal Verbs?

Modal verbs are a type of auxiliary verb that express conditions such as possibility, ability, necessity, or permission. They modify the meaning of the main verb, adding additional information about the likelihood or necessity of an action.

Definition:

Modal verbs are auxiliary verbs like can, should, and must that indicate possibility, intent, ability, or necessity.

Common Modal Verbs:

• • Can, could
  • May, might
  • Shall, should
  • Will, would
  • Must, ought to

Examples:

1. “I can swim.” (Ability)

2. “You must finish your homework.” (Necessity)

3. “It might rain today.” (Possibility)

Using Auxiliary Verbs

1. Altering the Tense Auxiliary verbs help change the tense of the main verb in a sentence. Examples:

• • Present Continuous: “She is writing an essay.”
  • Past Perfect: “They had eaten before the show started.”
  • Future Perfect: “I will have completed the project by tomorrow.”

2. Altering the Voice Auxiliary verbs help form the passive voice. Examples:

• • “The cake was baked by my mom.”
  • “The letters have been written by the students.”
  • “The task will be completed by the team.”

3. Expressing Mood The auxiliary verb “do” is used to emphasize mood in imperative or interrogative sentences. Examples:

• • “Do your homework now.” (Imperative)
  • “Did you complete the assignment?” (Interrogative)

Using Modal Verbs

1. Expressing Ability

• • “She can play the piano beautifully.”
  • “He could solve the puzzle when he was younger.”

2. Indicating Permission

• • “You may leave early today.”
  • “Can I borrow your book?”

3. Showing Necessity

• • “You must wear a helmet while riding a bike.”
  • “They have to complete the project by tomorrow.”

4. Expressing Possibility

• • “It might snow tonight.”
  • “She could win the race if she tries hard.”

5. Making Suggestions

• • “You should try the lasagna.”
  • “We ought to visit the museum.”

6. Forming Hypothetical Situations

• • “If I were you, I would accept the job offer.”
  • “She could have helped if she had been there.”

Auxiliary and Modal Verbs in Action

Verb Type	Verb	Usage	Example
Auxiliary	Be	Continuous tense	“He is studying for his exam.”
Auxiliary	Have	Perfect tense	“She has finished her work.”
Auxiliary	Do	Questions or negatives	“Do they like pizza?”
Modal	Can	Ability	“I can ride a bike.”
Modal	Must	Necessity	“You must complete the assignment.”
Modal	Should	Advice	“You should visit the doctor.”
Modal	Might	Possibility	“It might rain later.”

Practice Exercise: Fill in the Blanks

Fill in the blanks using the correct anomalous verb:

1. She ______ studying for the test. (Auxiliary verb: be)

2. You ______ finish your homework before going out. (Modal verb: necessity)

3. ______ he completed the project on time? (Auxiliary verb: do)

4. They ______ be at home now. (Modal verb: possibility)

5. We ______ been waiting for hours. (Auxiliary verb: have)

Answers:

1. is

2. must

3. Did

4. might

5. have

Frequently Asked Questions

Q1: What are auxiliary verbs?

Auxiliary verbs are helping verbs like “be,” “have,” and “do” used with main verbs to form tenses, moods, or voices.

Q2: What are modal verbs?

Modal verbs are auxiliary verbs like “can,” “must,” and “should” that express ability, necessity, permission, or possibility.

Q3: Can auxiliary and modal verbs be used together?

Yes, modal verbs can combine with auxiliary verbs to form complex sentences.

Example: “She might have been sleeping.”

Q4: What is the difference between auxiliary and modal verbs?

Auxiliary verbs form grammatical structures, while modal verbs add meaning, such as obligation, ability, or possibility.