Practice
Modal and auxiliary verbs: understand their roles
Sign in to saveCan and might are modal verbs, and they are also auxiliary verbs. Be, do, and have can be auxiliary verbs too, but they do different grammar jobs.
Tell modal verbs from other auxiliary verbs and use them to choose the right verb pattern in a sentence.
Read and practice
Read the examples and try the written questions in this guide. Listening recordings are not available for this lesson yet.
Try the written questions
Maya can join the call at noon. /ˈmaɪə kən dʒɔɪn ðə kɔːl æt nuːn/
The short answer
Modal verbs are a type of auxiliary verb. Use modals such as can, should, and might before a base verb to show ability, advice, obligation, or possibility. Use be, do, and have as other auxiliaries to build forms such as is working, did arrive, and has finished.
Maya can join the call at noon.
Why it works: Can is a modal auxiliary. It comes before the base form join.
4 more examples
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She is preparing the slides for tomorrow's meeting.
Is is an auxiliary that helps form the present continuous with preparing.
Not this:She
isthe meeting coordinator. What changes: Here is is the main verb, because it links She with the description meeting coordinator. -
Did you send the receipt to the office?
Did is an auxiliary that makes a past-tense question. Send stays in the base form.
Not this:You
didthe filing before lunch. What changes: Here did is the main verb. It means completed an action rather than helping another verb. -
We have finished the safety training.
Have is an auxiliary that helps form the present perfect with finished.
Not this:We
haveenough time for one more question. What changes: Here have is the main verb and means possess. -
The files might arrive before the deadline.
Might is a modal auxiliary that says an early arrival is possible but uncertain.
Not this:The files
will arrivebefore the deadline. What changes: Will presents the arrival as expected or intended, while might keeps the result uncertain.
Read the full guide
First, look at the job of the helping verb. Is it building the tense, making a question, or adding an idea such as ability or possibility? That job tells you whether you are looking at be, do, have, or a modal.
Start with the larger group
Auxiliary verb is the larger grammar term. An auxiliary works with a main verb. Modal verbs belong to that group, so every modal verb is an auxiliary verb. However, not every auxiliary verb is modal.
They might leave after the presentation.
Might is both a modal and an auxiliary. It adds the idea that leaving is possible, not certain.
They are leaving after the presentation.
Are is an auxiliary, but it is not modal. It helps form the present continuous.
Is every auxiliary verb a modal verb?
No. Be, do, and have can be auxiliary verbs, but they are not modal verbs.
Use be for continuous and passive forms
Be helps make continuous forms and passive forms. Its form changes with the subject and time: am, is, are, was, were, been, and being. Look for be followed by an -ing form or a past participle when you decide whether it is helping another verb.
The team is reviewing the proposal.
Is plus reviewing makes a present continuous form.
The proposal was approved yesterday.
Was plus approved makes a passive form. The proposal receives the action.
Which word is the auxiliary in The emails were sent this morning?
Were is the auxiliary. It helps form the passive with sent.
Use do and have for other grammar patterns
Use do to make many questions and negatives in the simple present and simple past. Use have to make perfect forms. These verbs may also be main verbs, so decide by looking at whether they help another verb or carry the main meaning themselves.
Does the store open at nine?
Does makes a present-simple question, while open stays in the base form.
I have checked the address twice.
Have helps form the present perfect with checked.
Choose the correct question: Did she called or did she call yesterday?
Use did she call. Did carries the past meaning, so call stays in the base form.
Use modal auxiliaries to add meaning
Modal auxiliaries do more than build a tense. They show the speaker's view of the action. Can can show ability or permission. Should gives advice. Must can show a rule or a strong conclusion. Might presents a possibility without a promise.
You should save a copy before you edit the file.
Should gives advice. The speaker recommends saving a copy.
Visitors must show identification at the entrance.
Must presents showing identification as a requirement.
Choose the modal for an uncertain plan: I ____ work from home on Friday.
Use might if working from home is possible but not decided.
Keep the verb after a modal in its base form
After a modal, use the base form of the next verb. Do not use to, -s, or -ing directly after can, should, must, or might. This pattern stays the same with every subject. In a question, put the modal before the subject.
He can solve the last problem.
Solve is the base form after can. Do not write can solves or can to solve.
Should we book the room now?
Should comes before we to make the question.
Correct this sentence: She might to arrive late.
Write: She might arrive late. Might is followed by the base form arrive.
Before you go
Remember this
Auxiliary verb is the larger category. Be, do, and have are primary auxiliaries; modal verbs are another group within the category. Choose a modal to add meaning such as ability, advice, or possibility, and choose be, do, or have when the grammar pattern needs one of those helpers.
Practice with the written examples
You can practice with the written questions in the Learn tab. Each answer includes an explanation.
Try the written questionsListening test not available yet
This lesson does not have the recordings needed for a listening test. Use the written questions in the guide to check your understanding.
Try the written questionsQuestions about "Modal and auxiliary verbs: understand their roles"
What is the difference between a modal verb and an auxiliary verb?
Auxiliary verb is the wider term for a helping verb. Modal verbs are one type of auxiliary verb. Can, should, and might add meanings such as ability, advice, and possibility. Be, do, and have are other auxiliaries that help make grammar patterns such as continuous, perfect, question, and negative forms.
She is preparing the slides for tomorrow's meeting.
Are be, do, and have modal verbs?
No. Be, do, and have are usually called primary auxiliaries when they help another verb. They are not modal verbs. Be can form continuous and passive patterns, do can make simple questions and negatives, and have can make perfect forms.
She is the meeting coordinator.
Can be, do, and have also be main verbs?
Yes. Their job depends on the sentence. In She is preparing, is helps make a continuous form. In She is the coordinator, is is the main linking verb. Similarly, have is an auxiliary in We have finished, but it is a main verb in We have enough time.
Did you send the receipt to the office?
What form comes after a modal verb?
Use the base form after a modal: can join, should save, must show, and might arrive. Do not add to, -s, or -ing directly after the modal. This is why Maya can join is correct, while Maya can joins is not.
You did the filing before lunch.
How do modal verbs change the meaning of a sentence?
Modal verbs add the speaker's meaning to the main verb. Can can show ability or permission, should gives advice, must can show a requirement, and might shows possibility without certainty. The main action may stay the same, but the modal changes how strongly the speaker presents it.
We have finished the safety training.