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Modal Verbs General Principles


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?


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).


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


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).

MODALS by function