Inflation

must to have to

must not not to be allowed to

can to be able to

may to be allowed to

need to have to

need not not to have to
Modal Verbs

A. express the speaker’s beliefs about or interpretation of the main action

You should get more exercise. (The speaker thinks this is a positive or even necessary course of action.)

You might find work on a farm. (The speaker thinks there is a weak possibility of finding work.)

B. share certain grammatical features that make them grammatically, but not semantically, interchangeable

• 
  invariable for all persons
  
• 
  occupy the position of the auxiliary verb in the sentence
  
• 
  are followed immediately by the base verb without to, except for ought to
  

12 Formal Modals and general semantic areas (not exhaustive)

semanticarea: potere	semanticarea: dovere	semantic area: futurity/conditionality/dovere
can	must	will	need
could	should	would	dare
may	oughtto	shall
might

Semi-modalforms

can	beableto	must	haveto
could		should	hadbetter
may	beallowedto	oughtto	besupposedto
might

Potere as:

ability, capacity	present	can beableto	I can speak French. This glass can hold 400 centilitres of liquid.
	past	could wasableto	I could swim when I was 10. He was able to swim to shore when the boat sank.
permission	present	may is allowed to can	You may not park here. cannot are not allowed to
	past	wasallowedto	When I was a child, girls were not allowed to wear trousers to school.

Potere as possibility/probability

present/ future	may	He may be at home. could might
	could
	might
past	mayhave	They may have told Sue. could might
	couldhave
	mighthave

Possibility/probability is an opinion

is will may could/might
factual certain prediction possible less possible

Jack is studying. (I know it for a fact.)

He will study all afternoon. (I feel very certain in predicting this.)
He may study all afternoon. (He has a test tomorrow.)
He could/might study all afternoon. (He has a test tomorrow but he is already well prepared.)

Dovere as obligation

at the moment of imposing authority or in the formulation of rules and regulations	must	You must finish in 30 minutes. (Teacher to students during an exam.) All vehicles must display a parking permit. (Sign at car park entrance.)
referringtoimposedauthority	haveto	You have to have a parking permit to park here.
generalnecessity	have to need (only neg and questions)	He has to go to the bank. You needn’t worry, everything is ok.

past –
must and have to both become had to

We had to finish in 30 minutes.
He had to go to the bank.

negative –

You must not use a dictionary. (It is forbidden.) vs. He doesn’t have to use a dictionary/He needn’t use a dictionary. (It’s not necessary, he knows the language well.)

Dovere as logical supposition/deduction

present -
He’s late. He must be stuck in traffic.
No one is answering the phone. They must not be at home.
They can’t be out. The car is in the driveway.
past -
They missed the concert even if they are big fans. They must not have been able to get tickets.
They love that group. They must have seen the concert.

Dovere as advice

You should stop smoking.
ought to
had better

NB. had better implies that there could be negative consequences if we do not follow the advice given us.

Dovere to indicate a wise, proper or morally correct course of action
present
You should never bet more money than you can afford to loose.
You should show respect to the elderly.

past
He should have called a lawyer before speaking with the police.

Dovere to indicate plans
He should be on a train to Rome now.
They are supposed to arrive tomorrow evening.
(This was the arrangement but the speaker is not 100% certain this is happening/will happen.)

He was supposed to call at 3 o’clock.

(This was the arrangement, but it didn’t happen.)

Will
futurity – most common use

obligation – the language of contracts
The renter will vacate the premises by 30 June.
The supplier will pay a penalty of 10% for deliveries effected more than 15 days after terms of contract.

would

• 
  conditionals
  

I would buy a new car if I had more money.

• 
  politerequests
  

Would you hand me that book, please?

• 
  futureinthepast
  

It would be more than 3 days before we reached the coast of South America.

shall

• 
  to offer to do something for someone
  

Shall I turn on the light?

• 
  tomakesuggestions
  

Shall we go out for a change instead of sitting in front of the TV?