MODAL VERBS
They have the same form in all persons.
Modal
verbs
They come before the subject in questions and take “not” after them in negations.
They take an infinitive without “to” after them.
Can she sing? No, she can’t sing but she can dance.
Can is used to express ability in the present or to ask permission.
Can
Could is used to express ability in the past, polite requests or to ask permission politely.
(could)
She can type. (ability in the present)
Can I borrow your pen? (asking permission)
He could run fast when he was 17. (ability in the past)
Could I have some tea? (polite request)
Could I leave early, please? (asking permission)
Must and have to are used to express necessity or obligation.
Must
“ Have to ” means that sb else decides.
“ Must ” means that I decide.
(have to)
“ Must ”
“ Have to / has to ”
(“don’t/doesn’t have to”)
It’s raining. I must take my umbrella. (necessity)
I must do my homework. (obligation)
He has to go to hospital. (necessity)
Present tense
Soldiers have to wear a uniform.
I must work till late tonight.
“ Had to ”
(“didn’t have to)
Past tense
Must expresses obligation or necessity.
Must
Mustn’t
Needn’t
Mustn’t expresses prohibition.
Needn’t expresses no necessity.
You must tell the truth.
You mustn’t drive fast.
There’s enough bread. You needn’t buy any.
Shall is used with “I” or “We” in questions, suggestions or offers.
Shall
Will
Would
Will is used to express predictions, warnings, offers, promises, threats, requests, suggestions, on-the-spot decisions, opinions, hopes and fears.
(would like)
Would is used to express polite or formal requests.
Shall we go to the cinema tonight?
Try harder or you’ll fail your exams.
Would you carry my suitcase?
Would you like to come with me to the party?
Would like is used to express polite or formal offers and suggestions.
Ability
Can
ability in the present or future
ability in the past for repeated actions
Could/ was able to
=managed to; ability in the past for repeated actions or a single action
Was able to
for repeated or single actions
Couldn’t/ wasn’t able to
Possibility/probability
May
perhaps, very possible (present form; be allowed to)
Might
perhaps, very possible (past form)
possible
Could
it is almost certain; I think
Must
it does not seem possible; I don’t think
Can’t
Is it possible?
Can he be?
Permission
Can
informal
Could
more polite
May
formal
more formal
Might
Giving/refusing permission
Can
informal, giving permission
May
formal, giving permission
Mustn’t
refusing permission
refusing permission
Can’t
Requests, offers or suggestions.
Can
request
Could
polite request/suggestion
Would you like
polite offer
Shall I/we
suggestion/offer
Will
offer/request
Advice
Should/ought to
general advise; I advise you
Had better
advice for a specific situation; it’s a good idea
You should walk more.
You’ d better see your dentist.
Obligation/necessity
Must
strong obligation or personal feelings of necessity
Have to
external necessity
I’ve got to
informal; it’s necessary
Absence of necessity or prohibition
Mustn’t
prohibition
Can’t
prohibition
Needn’t
it is not necessary
Don’t need/have to
it is not necessary in the present/future
Didn’t need/have to
it was not necessary in the past