Modal Verbs General Principles

Form

All Modal verbs are followed by the Infinitive without to except in the past where they are followed by ‘have + Past Participle’. Remember that ‘Have to’ and ‘Ought to’ are considered to be Modal verbs which already contain ‘to’.

 

Present - Subject + Modal + Infinitive without to

 

Past – Subject + Modal + Have + Past participle

 

+  She can sing opera                                                                              We have to renew our passports

-  You shouldn’t take drugs                                                                     You ought not to do that

?  Would you tell a lie?                                                                             Do we have to recycle everything?

Function

The function of each modal is quite specific depending on whether they are Modals of possibility, ability, deduction, etc. In general they are thought of as ‘helping’ verbs that ‘moderate’ the main verb.

 

- Can you fly?

- No, I can’t. Can you?

- No, but I would if I could.  =

 

- Can you fly?

- No, I can’t (fly). Can you (fly)?

- No, but I would (fly) if I could (fly).

Exceptions

Great news. There are no exceptions. HOWEVER certain modal verbs have no forms for Past, Perfect or Future tenses.

 

These are: CAN for ability, which sometimes has to change to a form of BE ABLE TO

 

In the future I WON’T BE ABLE TO run so fast

 

HAVE you BEEN ABLE TO do all that work?

 

And: MUST, which changes to a form of HAVE TO

 

At infant school I HAD TO wear short trousers

 

WILL we HAVE TO bring our own sandwiches?

Spelling notes:

As the modals don’t change form there are no spelling difficulties to consider

Pronunciation

Modals are often ‘elided’ (run together) just as in fast Speech ‘want to’ becomes ‘wanna’. Here are some other examples to look for

 

I gotta (godda in American English) = I have got to = I have to

 

I hafta = I have to

 

And the ‘have’ in Past Modals can sound like:

 

cudda, shudda, etc.

I could have been a boxing champion

 

You should have closed the door

 

(NEGATIVE – You shudentav: You shouldn’t have hit the policeman).

Can

Ability

Possibility

Permission

Informal Requests

Could

Past form of "Can"

Polite Requests

Possibility

Dare
Have to
May

Possibility

Ask or give permission (formal)

Might

Past form of "May"

Possibility

Must

Obligation

Deduction of certainty

Prohibition (Must not)

Need
Ought to

Moral Obligation

Shall

Future (formal or emphatic)

Questions and suggestions

Should

Moral Obligation

To emphasise a discovery that was not expected

Advice

Predictions of things that are expected

Used to