• What are modal verbs?

Modals (also called modal verbs, modal auxiliary verbs, modal auxiliaries) are special verbs which behave irregularly in English. They are different from normal verbs like “work, play, visit…” They give additional information about the function of the main verb that follows it. They have a great variety of communicative functions.

  • What to keep in mind when using modals
Explanation Sample sentences
Do not use modals for things which happen definitely. The sun rises in the east. – A modal can’t be used in this sentence.
They have no -s in the 3rd person singular. He can play football.
Questions are formed without do/does/did. Can he speak Spanish?
It follows a main verb in its infinitive. They must read the book.
There are no past froms (except could and would). He was allowed to watch the film.
When you use the past particple you tell about things which did not happen in the past. You should have told me.
  • Long and contracted forms of modals
Affirmative Negative
Long forms Contracted forms Long forms Contracted forms
can cannot can’t
could could not couldn’t
may may not
might might not
ought to ought not to oughtn’t to
need need not needn’t
shall ‘ll shall not shan’t
should ‘d should not shouldn’t
will ‘ll will not won’t
would ‘d would not wouldn’t
  • Examples of modal verbs

Here is a list of modals with examples:

Modal Verb Expressing Example
must Strong obligation You must stop when the traffic lights turn red.
logical conclusion / Certainty He must be very tired. He’s been working all day long.
must not prohibition You must not smoke in the hospital.
can ability I can swim.
permission Can I use your phone please?
possibility Smoking can cause cancer.
could ability in the past When I was younger I could run fast.
polite permission Excuse me, could I just say something?
possibility It could rain tomorrow!
may permission May I use your phone please?
possibility, probability It may rain tomorrow!
might polite permission Might I suggest an idea?
possibility, probability I might go on holiday to Australia next year.
need not lack of necessity/absence of obligation I need not buy tomatoes. There are plenty of tomatoes in the fridge.
should/ought to 50 % obligation I should / ought to see a doctor. I have a terrible headache.
advice You should / ought to revise your lessons
logical conclusion He should / ought to be very tired. He’s been working all day long.
had better advice You ‘d better revise your lessons

Let’s look at each modal verb separately, and the functions they help to express:

  1. WILL
  • Making personal predictions
    I don’t think the Queen will ever abdicate.
    I doubt if I’ll stay here much longer.
  • Talking about the present with certainty (making deductions)
    I’m sure you will understand that there is nothing the Department can do
    There’s a letter for you. It’ll be from the bank: they said they’d be writing.
  • Talking about the future with certainty
    I won’t be in the office until 11; I’ve got a meeting.
    Don’t bother ringing: they’ll have left for their 10 o’clock lecture.
  • Talking about the past with certainty
    I’m sure you will have noticed that attendance has fallen sharply.
  • Reassuring someone
    Don’t worry! You’ll settle down quickly, I’m sure.
    It’ll be all right! You won’t have to speak by yourself.
  • Making a decision
    For the main course I’ll have grilled tuna.
    I’m very tired. I think I’ll stay at home tonight.
  • Making a semi-formal request
    Will you open the window, please? It’s very hot in here.
    Sign this, will you?
  • Offering to do something
    You stay there! I’ll fetch the drinks.
  • Insistence; habitual behaviour
    I’m not surprised you don’t know what to do! You will keep talking in class.
    Damn! My car won’t start. I’ll have to call the garage.
  • Making a promise or a threat
    You can count on me! I’ll be there at 8 o’clock sharp.
    If you don’t finish your dinner off, you’ll go straight to bed!

    2. SHALL

Shall is a form of will, used mostly in the first person. Its use, however, is decreasing, and in any case in spoken English it would be contracted to “-ll” and be indistinguishable from will.

The only time you do need to use it is in questions, when:

  • Making offers
    Shall I fetch you another glass of wine?
  • Making suggestions
    Shall we go to the cinema tonight?

    3. MAY & MIGHT

May & might sometimes have virtually the same meaning; they are used to talk about possibilities in the past, present or future. (“Could” is also sometimes used).

May is sometimes a little bit “more sure” (50% chance); whereas might expresses more doubt (maybe only a 30% chance).

May & might are used, then, for:

  • Talking about the present or future with uncertainty
    I may go shopping tonight, I haven’t decided yet.
    England might win the World Cup, you never know.
  • Talking about the past with uncertainty
    I’m surprised he failed. I suppose he might have been ill on the day of the exam.
    They can also sometimes be used for talking about permission, but usually only in formal situations. Instead of saying May I open a window? we would say Is it all right/OK if I open a window? or Can I open a window? for example. You might, however, see:
    Students may not borrow equipment without written permission.

    4. MAY

  • Talking about things that can happen in certain situations
    If the monitors are used in poorly lit places, some users may experience headaches.
    Each nurse may be responsible for up to twenty patients.
  • With a similar meaning to although
    The experiment may have been a success, but there is still a lot of work to be done. (= Although it was a success, there is still …)


Saying that something was possible, but did not actually happen

You saw me standing at the bus stop! You might have stopped and given me a lift


  • As the past of will, for example in indirect speech
    “The next meeting will be in a month’s time” becomes
    He said the next meeting would be in a month’s time.
  • Polite requests and offers (a ‘softer’ form of will)
    Would you like another cup of tea?
    Would you give me a ring after lunch?
    I’d like the roast duck, please.
  • In conditionals, to indicate ‘distance from reality’: imagined, unreal, impossible situations
    If I ruled the world, every day would be the first day of Spring.
    It would have been better if you’d word processed your assignment.
  • After ‘wish’, to show regret or irritation over someone (or something’s) refusal or insistence on doing something (present or future)
    I wish you wouldn’t keep interrupting me.
    I wish it would snow.

    (This is a complicated area! Check in a good grammar book for full details!)
  • Talking about past habits (similar meaning to used to)
    When I was small, we would always visit relatives on Christmas Day.
  • Future in the past
    The assassination would become one of the key events of the century.


  • Talking about ability
    Can you speak Mandarin? (present)
    She could play the piano when she was five. (past)
  • Making requests
    Can you give me a ring at about 10?
    Could you speak up a bit please? (slightly more formal, polite or ‘softer’)
  • Asking permission
    Can I ask you a question?
    Could I ask you a personal question? (more formal, polite or indirect)
  • Reported speech
    Could is used as the past of can.
    He asked me if I could pick him up after work.
  • General possibility
    You can drive when you’re 17. (present)
    Women couldn’t vote until just after the First World War.
  • Choice and opportunities
    If you want some help with your writing, you can come to classes, or you can get some 1:1 help.
    We could go to Stratford tomorrow, but the forecast’s not brilliant. (less definite)
  • Future probability
    Could (NOT can) is sometimes used in the same way as might or may, often indicating something less definite.
    When I leave university I might travel around a bit, I might do an MA or I suppose I could even get a job.
  • Present possibility
    I think you could be right you know. (NOT can)
    That can’t be the right answer, it just doesn’t make sense.
  • Past possibility
    If I’d known the lecture had been cancelled, I could have stayed in bed longer.


Examples here refer to British English; there is some variation in American English.

  • Necessity and obligation

Must is often used to indicate ‘personal’ obligation; what you think you yourself or other people/things must do. If the obligation comes from outside (eg a rule or law), then have to is often (but not always) preferred:

I really must get some exercise.
People must try to be more tolerant of each other.
You mustn’t look – promise?
If you own a car, you have to pay an annual road tax.

  • Strong advice and invitations
    I think you really must make more of an effort.
    You must go and see the film – it’s brilliant.
    You must come and see me next time you’re in town.
  • Saying you think something is certain
    This must be the place – there’s a white car parked outside.
    You must be mad.
    What a suntan! You must have had great weather.

  • The negative is expressed by can’t:
    You’re going to sell your guitar! You can’t be serious!
    She didn’t wave – she can’t have seen me.


  • Giving advice
    I think you should go for the Alfa rather than the Audi.
    You shouldn’t be drinking if you’re on antibiotics.
    You shouldn’t have ordered that chocolate dessert – you’re not going to finish it.

  • Obligation: weak form of must
    The university should provide more sports facilities.
    The equipment should be inspected regularly.
  • Deduction
    The letter should get to you tomorrow – I posted it first class.
  • Things which didn’t or may/may not have happened
    I should have renewed my TV licence last month, but I forgot.
    You shouldn’t have spent so much time on that first question.
  • Ought to
    Ought to usually has the same meaning as should, particularly in affirmative statements in the present:
    You should/ought to get your hair cut.
    Should is much more common (and easier to say!), so if you’re not sure, use should.



1. There are plenty of tomatoes in the fridge. You ____ buy any.

a. needn’t              b. may not           c. mustn’t

2. It’s a hospital. You ____ smoke.

a. needn’t          b. don’t have to             c. mustn’t

3. If you want to learn to speak English fluently, you ____ to work hard.

a. needn’t          b. need           c. could

4. ____ I ask a question? Yes, of course.

a. may          b. must          c. should

5. You ____ leave small objects lying around . Such objects ____ be swallowed by children.

a. need & may          b. shouldn’t & may            c. may not & must

6. The teacher said we ____ read this book for our own pleasure as it is optional. But we ____ read it if we don’t want to.

a. must & could             b. needn’t & mustn’t            c. can & can







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