Modal Auxiliaries

These auxiliaries affect the mood of the verb; that is, they determine whether a verb is a fact, desire, possiblity, or command. They are most commonly used to represent degrees of freedom or severity.

Most common modal auxiliaries:
will, shall, can, may, need (to), dare, would, should, could, might, must, ought (to)

Ability: I can run.Necessity: I must run.Obligation: I ought to run.Permission: I may run.

Defective Modal Auxiliaries

usually only exist in the Present and Past (or only in ONE Tense) have no infinitives (no: to can!) have no direct objects (I can do it not: I can it) do not have an -s in the third person singular: he can (Present Tense) simply use NOT as a negation: he may not, he cannot (spelling!) there is no TO between the auxiliary and the full verb: he can come

 

 

Simple Present	Simple Past	Substitute
I can	I could	to be able to
I may	I might	to be allowed / permitted to
I shall	I should	to be to
I will	I would	to want / wish / desire / intend to
I must	------------	to have to / to be obliged to / to be forced to / to be compelled to
----------	I ought to	-------------
	I used to	I would / to be in the habit of (doing s.th.)
I dare*	-----------	to dare to
I need	----------	to need to

 

*(The Guardian, Friday February 28, 2003: The glory that is Brum
How dare Birmingham, a city chiefly known for spawning Ozzy Osbourne and a laughably adenoidal accent, presume to join a list of truly great cities such as Paris, Florence and Amsterdam as a European City of Culture? )

Some tests under:
http://www.miguelmllop.com/practice/beginners/tenserevision/modalauxiliaries1.htm
http://www.homepage.bnv-bamberg.de/englischinteraktiv/modalauxiliaries1.htm