The use of modals
Modal auxiliaries are followed by bare infinitives. Mind you, the infinitive is not the first form of the verb. The first form of the verb is only one type of the infinitive (it is the simple infinitive).
Johnny could go home after class. (simple infinitive)
You must be joking. (continuous infinitive)
He may have caught the train. (perfect infinitive)Jimmy must have been sleeping. (perfect continuous infinitive)
That could be the reason why he missed the film. (simple infinitive)
Very often we refer to the past with a present modal and a perfect infinitive:
You should have eaten more. (Present modal + perfect infinitive = past reference)
For the sake of convenience we refer to modal idioms, semi auxiliaries and similar structures asmodals.
A modal idiom contains a modal and a to + infinitive or an adverb: be to, had better, have got to etc.
Semi-auxiliaries are verb idioms introduced by have or be: be able to, be likely to, have to etc.
Similar structures include: need to, be likely that, be allowed to etc.
Semi-auxiliaries are important to know so that you will be able to express ideas for which you wouldneed two or more modals:
If you want to be a sailor, you must can swim.
If you want to be a sailor, you must be able to swim.
I have canned swim since the age of 6.
I have been able to swim since the age of 6.
The first and the third sentence above are incorrect, partly because a modal cannot be followed by another modal but only by an infinitive, and also because they haveno -ing or -ed forms.
What are Modal Verbs?
Modal verbs are special verbs which behave very differently from normal verbs. Here are some important differences:
1. Modal verbs do not take "-s" in the third person.
• He can speak Chinese.
• She should be here by 9:00.
2. You use "not" to make modal verbs negative, even in Simple Present and Simple Past.
• Heshould not be late.
• They might not come to the party.
3. Many modal verbs cannot be used in the past tenses or the future tenses.
• He will can go with us. Not Correct
• She musted study very hard. Not Correct
Common Modal Verbs
|Can |Ought to |
|Could |Shall |
|May |Should |
|Might |Will |
|Must |Would |
For the purposes of this tutorial, we have included some expressions which are not modal verbs including had better, have to, and have got to. These expressions are closely related to modals in meaning and are often interchanged with them.
Ability, less used than can
E.g. I’m not able tocome to the game on Friday.
E.g. can you play the piano?
Asking for and giving permission
e.g. “Mom, can I go the cinema tonight?”
“No, you can’t. You have homework to do”
e.g. Can I help you?
e.g. Can you switch on the light for me?
e.g. The summers in England can be really unpredictable.
With be to makecriticisms
E.g. Susan can be a real pain in the neck at times.
E.g. I can’t come to the game on Friday.
When you feel sure something is not possible (opposite of must)
e.g. The tennis match can’t be over yet. (I’m sure it isn’t).
Possibility or uncertainty (can also use might)
e.g. He could be the one for you!
Request (more polite than can)
e.g. Could youswitch on the light for me?
e.g. We could go on a picnic this afternoon.
Asking for and giving permission
e.g. “Could I use your phone?”
“Yes, of course you can”
e.g. I couldn’t possibly leave Tom alone while he’s in this state.
With comparative adjectives to express possibility or impossibility
E.g. I could be fitter.
E.g. He couldn’t...