Grammar: Modal Verbs

CouldShouldWouldWould you like to learn how to use modal verbs? Maybe we should learn about them, but could we learn about them? We may learn about modals, but then again, we may not. We might be able to learn about them here. In fact, we could learn about modals right now! Yes, we will learn about modals! Let’s learn how to use modal verbs!

Modal verbs function in English as auxiliary verbs; they indicate the likelihood, ability, obligation, or permission of the main verb.  Modal verbs are different than most verbs in English in three ways:

  • They never take an “s” at the end in the present third person singular. For example, “could” stays “could” whether I could, you could, or she could.This is different than most verbs, for instnace, “to walk,” which changes: I walk, she walks, you walk.
  • They make questions by inversion, like the word “do.” For example, the statement “She would like potatoes.” becomes the question “Would she like potatoes?” when “she” and “would” switch places.
  • They are immediately followed by another verb in the infinitive tense, but without “to.” For example “I can swim a mile,” and “We might go bowling,” are correct, but not “I can to swim a mile,” and “We might to go bowling“. This is unlike other helping verbs, which keep the “to” in front of the infinitive. For instance: “I want to swim a mile” is correct.

The main modal verbs in American English are can, could, may, might, must, should, will and would. “Shall” is more often used in British English, and “ought to” and “had better” usually work exactly like modals and are often included among modal lists. Modals can be overwhelming; there are a LOT of them, and their differences and meanings are often subtle. There will be more in-depth posts about modals soon. In the meantime, here’s a chart to get you started.


Modal Function Examples
Can To Show Ability I can walk on stilts.
To Suggest Possibility or Give Options Students can choose either physics or biology classes for their science requirement.
To Show Impossibility My dog can’t be in the park; I left her at home.
To give or ask for Permission (informally) Can I borrow your car tonight? You can borrow it if you bring it back by midnight.
Could Past Tense of “Can.” I could walk on stilts when I was ten years old.
Past Permission He said I could visit him on Thursday.
To Show Possibility Lucy could be coming to this party.
To Show Impossibility Lucy couldn’t be at the movies; she’s at the party!
Make a Request, Offer, or Suggestion I could help you with your math homework.You could try cleaning it with vinegar.
May To Show Possibility He may know the answer.
To Give or Ask For Permission Formally May I turn my paper in a day late? You may turn your paper in tomorrow or Monday.
Might Past Tense of “May” He said he might not wait for us.
Show Possibility I might have dropped my keys in the park.
Must To Show Necessity You must be careful when you use knives.
To Show Prohibition You must not wake the children.
To Show Deduction/Probability He’s been studying for 24 hours; he must be exhausted.
Should (& Ought to) To Give or Ask for Advice Should I go to the new gym in town?You should go; they have a climbing wall.
To Show Obligation I should start organizing my taxes.
To Show Expectation I ordered it on Monday, so it should be here any time.
Will To Show Predictions/Inevitability Gas prices will be lower this summer.

I will pass this exam.

To Show Promises and Intentions I will pick you up at the airport.
Would Past Tense of “Will” He said he would pick me up at the airport.
For Imagined Situations What would you do if you won the Lottery?
For Polite Requests, Invitations, and Offers Would you like to go to the beach with us?Would everyone please take a seat?
To Express Willingness I would carry that suitcase for you.
To Express Desires I would rather go to the mountains than the lake.
To Express Tendencies She wouldn’t steal your money.
To Express Past Habits My Freshmen year, I would often eat dinner in the Library.
Shall To Show Future action (with I and We) We shall open at 10:00 am tomorrow.
Polite Suggestions Shall we go?
To Show Inevitability We shall overcome oppression.
Had Better To Show Warning You had better come in out of the rain before you catch cold.
Desperate Hope The bus had better get here soon, or I’ll be late.