This document discusses the use of modal verbs in English grammar. It covers: 1. The main modal verbs are can, could, may, might, must, will, would, shall, should, ought to. They are used to "help" another verb and have specific grammatical forms. 2. Each modal verb has multiple meanings, such as expressing possibility, permission, obligation or making requests/offers. 3. Modal verbs are used to express attitudes and opinions, for example "It could/may/might/must/should be Henry knocking at the door." 4. Obligation is expressed by must, have to, should and ought to, with subtle differences in meaning

1. THESE GRAMMAR NOTES REFER TO THE USE OF MODAL VERBS
MODAL VERBS
The Modal Verbs are: can, could, may, might, must, will, would, shall, should, ought to. They are
known as ‘modal auxiliary verbs’ because they ‘help’ another verb:
I can swim. Do you think I should go?
FORM
1. There is no –s in the third person singular:
She can swim; he must be tired; it might rain later.
2. There is no DO/DOES in the question:
Shall we go for a walk? Can I help you? What should I do?
3. There is no DON’T/DOESN’T in the negative:
He can’t dance; I won’t be a minute; you mustn’t steal.
4. Modal auxiliary verbs do not usually have past forms. Other expressions are used instead:
I had to work very hard at school; COULD is used with a past meaning in some cases.
5. They have no infinitives and no –ing forms. Other expressions are used instead:
I’d love to be able to ski; I hate having to get up on cold mornings.
6. They are followed by infinitive without to:
You must go; I’ll help you.
Ought to is the exception: you ought to see a doctor.
7. They can be used with perfect infinitives to talk about the past:
You should have told me that you can’t swim: you might have drowned!
USE
Each modal verb usually has at least two meanings.
1. One use of all of them is to express possibility or probability:
I must post this letter (= obligation); you must be tired (= deduction, probability); could you
please help me? (= request); we could go to Portugal (= possibility, suggestion); may I go now?
(= permission); Hannah may be at work now (= possibility)
2. Modal verbs express our attitudes, opinions and judgements of events.
‘Who’s that knocking at the door?’ ‘It could/may/might/must/should/can’t/’ll be Henry’.
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2. OBLIGATION is expressed by must / have to / should / ought to.
We don’t usually use must in questions, although it is possible: must I …?
Have to has all the forms that must does not have:
I had to work yesterday (past); you will have to attend that seminar (future); she has never had to
commute (present perfect); I hate having to cook (-ing form); if you were a teacher, you would have
to be very patient (infinitive).
Should expresses weak obligation and is often accompanied by sentences like ‘do you think’: do
you think I should apply for that job?
MUST is used to express an obligation that invo lves the speaker’s opinion; it is personal:
I must get my hair cut (this is me talking to myself); I must write to Anne: I haven’t written to her
for ages! (the speaker personally feels that he must do it);
must is also associated with a formal, written style: candidates must answer all questions
(instructions on an exam paper).
HAVE TO expresses a general obligation based on a law or rule or based on the authority of
another person. It is more objective : I have to go to my GP (I have an appointment); in many
English-speaking countries you have to drive on the left.
Sometimes the two verbs are interchangeable: I must/have to be back by midnight.
MUSTN’T / DON’T HAVE TO are very different! Mustn’t expresses a negative obligation – it is
important NOT to do something: you mustn’t steal other people’s things; don’t have to expresses
the absence of obligation: you don’t have to come tomorrow (it is not necessary).
You can always use HAVE GOT TO, especially in British English.
EXPRESSING PERMISSION: can / may / be allowed to are used to express permission:
you can borrow my bike;
may we smoke here?
You are not allowed to use mobiles.
MAKING REQUESTS : can / could / will / would
You can also use the following:
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3. Would you mind filling in this form?
Do you mind if I open the door?
Would you mind if I opened the door?
MAKING OFFERS: will and shall are used in such cases: shall we go out for a pizza? (shall is
used only for I and we)
MAY / MIGHT express possibility in the present or future: take your umbrella as it might rain; we
may go to Paris on holiday.
Examples of modals in the past:
MODAL + HAVE + PAST PARTICIPLE
(for the negative add NOT to the modal verb)
You might have left your wallet in the shop (= perhaps you have left it there)
Robert must have gone out (now he’s not in).
She passed me in the street without speaking: she can’t have seen me.
I rang Helen but she did not reply, so I suppose she may have been in the bath.
Sandy did not come to the meeting: he might not have known about it.
Sometimes modal verbs can be structured in the continuous form (instead of being followed by
infinitive) when you talk about possible plans:
MODAL VERB + BE + -ING FORM
I may/might be going to Belgium in December (I may go = it’s a possibility).
I really should be going now (I should go right now!).
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