Modals are special verbs, sometimes known as auxiliary verbs. A modal verb always has the same form and never has the -s, -ing or -ed suffixes. That means, modal verbs are always followed by the base form. Here’s a list of modals:

MODALS

  • can
  • could
  • must
  • should
  • ought
  • may
  • might
  • will
  • would
  • shall

Look at the following examples. You will see that modals are followed by the base word come instead of came or coming, and run instead of ran or running:

Examples:

  1. You can come in when you’re ready. (√)
    You can came in when you’re ready. (X)
  2. We should run if you want to catch the bus. (√)
    We should ran if you want to catch the bus. (X)

Functions of modal verbs in sentences

Modals

Examples

Functions

can
  • They can run fast.
  • We can’t see the road.
  • Can I stay over tonight?
  • Can you help me?
  • Ability, Possibility
  • Inability, Impossibility
  • Asking for permission
  • Request

could
  • Could I leave the room now?
  • Could you please repeat?
  • You could try again later.
  • There could be another war.
  • I thought he could, but he can’t.
  • Asking for permission.
  • Request
  • Suggestion
  • Future possibility
  • Ability in the past

may
  • May I carry your luggage?
  • If things don’t change, we may have to close our business.
  • Asking for permission
  • Future possibility

might
  • I might be at home, I’m not sure.
  • They might be praying now, so it’s better to call later.
  • Future possibility
  • Present possibility

must
  • You mustn’t smoke in campus.
  • It’s getting late. I’m afraid we must go.
  • Prohibition
  • Necessity, Obligation

ought to
  • She ought to see a doctor. She has been complaining since yesterday.
  • Saying what’s right or correct

shall
  • Shall I open the door for you?
  • Shall we leave in half an hour?
  • Offer
  • Suggestion

should
  • We should call for a meeting now; it’s urgent.
  • You should check the expiry date.
  • Recession should be over next year.
  • Saying what’s right or correct
  • Recommending action
  • Uncertain prediction

will
  • I’ll do that for you if you like.
  • I’ll get you a bike if you do well in the exam.
  • I believe it will rain this evening.
  • Offer
  • Promise
  • Certain prediction

would
  • Would you mind if I smoked?
  • Would you help us, please?
  • Would 9 A.M. be fine with you?
  • Would you like to see my house?
  • Would you prefer coffee or tea?
  • Asking for permission
  • Request
  • Making arrangements
  • Invitation
  • Preferences

Take note that modals change form in the past and future tenses. For example:

  • I can do it. – present tense
  • I could do it just now. – past tense
  • I could do it later today. – future tense

The table above gives some example sentences to illustrate this point.