Modals, Auxiliaries

be, have and do can be auxiliaries und full verbs.
Modals are: can, could, may, might, must, ought to, shall, should, will, would and need
(need can be a full verb, too).

We can play football.

We could play football.

We may play football.

We might play football.

We must play football.

We mustn't play football.

We needn't play football.

We ought to play football.

We shall play football.

We should play football.

We will play football.

We would play football.

Note:

1)	Do not use modals for things which happen definitely.	The sun rises in the East.
2)	They do not have an -s in the 3rd person singular.	He can play football.
3)	Questions are formed without do/does/did.	Can he speak Spanish?
4)	It follows a full verb in the infinitive.	They must read the book.
5)	There are no past forms (except could and would).	He was allowed to watch the film.
6)	When you use the past particple, you tell about things which did not happen in the past.	You should have told me.

Form

positive		negative
long form	contracted form	long form	contracted form
can	--	cannot	can't
could	--	could not	couldn't
may	--	may not	--
might	--	might not	--
ought to	--	ought not to	oughtn't to
--	--	need not	needn't
shall	'll	shall not	shan't
should	'd	--	shouldn't
will	'll	will not	won't
would	'd	would not	wouldn't