MODAL VERBS
Only used in
one form
( no past, no –ing form,
no –s in 3rd person
singular)
Negative :
place not
after the
modal verb
never
conjugated
MODAL VERBS
Express an idea
(possibility,necessity,
obligation etc
Always come
before subject
in interrogative
sentences
Always followed
by a main verb
in the base form
CAN
PERMISSION OR
ABILITY/INABILITY
REQUEST
I can play the piano.
Can I call you
later?
OPPORTUNITY TO DO
SOMETHING/POSSIBILITY
I´m free tonight so we can
go out.
CAN – affirmative and negative forms
I
You
He
She
It
We
they
+ CAN
- CAN´T
CANNOT
Verb in the
base form
+
complements
ATTENTION!
Can´t/cannot
indicate
impossibility
CAN – negative form
CAN
I
You
He
She
It
We
You
they
MAIN VERB IN
THE BASE
FORM
+
COMPLEMENTS
+
?
COULD
PAST OF
CAN
PAST
ABILITY
.
When I was
young, I could
ride a bike.
MORE
POLITE
THAN CAN
(REQUEST)
Could you open the
door, please?
POSSIBILITY
I think we could have
another Gulf war.
COULD – affirmative and negative forms
I
YOU
HE
SHE
IT
WE
THEY
+ COULD
MAIN VERB IN
THE BASE FORM
+
-COULD NOT
- COULDN´T
COMPLEMENTS
ATTENTION!
COULD NOT
Suggests that
it´s impossible
for something to
happen
COULD – interrogative form
COULD
I
YOU
HE
SHE
IT
WE
THEY
MAIN VERB IN
THE BASE
FORM
+
COMPLEMENTS
+
?
MUST
DEDUCTION OR
CENTAINTY
That must be Jerry,
they said he is tall and
has red hair.
OBLIGATION
(“must” involves the
speaker´s authority or
opinion)
You must go to bed, said
her mum
MUST – affirmative and negative

+ MUST
MAIN VERB IN
THE BASE FORM
+
- MUST NOT
MUSTN´T
COMPLEMENTS
MUST NOT = MUSTN´T
PROHIBITION
You must not swim in that river, it is full of
crocodiles
MUST - interrogative
MUST

MAIN VERB IN
THE BASE
FORM
+
COMPLEMENTS
+
?
MAY
Possibility
He may run the
marathon this
year
Polite
permission or
request
May I go now?
Yes, you may
MAY – affirmative and negative forms

+ MAY
- MAY
NOT
MAIN VERB IN
THE BASE
FORM
+
COMPLEMENTS
ATTENTION!
THERE IS NO
ABBREVIATION
FOR MAY NOT
MAY - interrogative
MAY

MAIN VERB IN
THE BASE FORM
+
COMPLEMENTS
+
?
MIGHT
To say that you are not sure that
something is going to happen
She might come to my house later.
MIGHT – affirmative and negative forms

+ MIGHT
MAIN VERB IN
THE BASE
FORM
+
- MIGHT
NOT
COMPLEMENTS
ATTENTION!
IT´S NOT
USUALLY USED
IN
INTERROGATIVE
FORM.
MAY x MIGHT x COULD
HAVE/HAS TO
OBLIGATION
( based in a law or rule)
I have to wear a uniform in my
school
DON´T/DOESN´T HAVE TO
It is not necessary to do something, you
can do it if you want but it is not
necessary
She doesn´t have to finish her composition
tonight
HAVE/HAS TO – affirmative form
She
He
it
HAS
MAIN VERB IN THE
BASE FORM
TO
+
COMPLEMENTS
I
YOU
HAVE
WE
TO
THEY
MAIN VERB IN
THE BASE FORM
+
COMPLEMENTS
HAVE TO – interrogative form
MAIN VERB IN
THE BASE FORM
He
She
It
DOES
HAVE
TO
+
COMPLEMENTS
+
?
I
DO
YOU
HAVE
WE
TO
THEY
MAIN VERB IN THE
BASE FORM
+
COMPLEMENTS
+
?
SHOULD
ADVICE
SUGGESTIONS
CRITICISM
EXPECTATIONS
This film should be good.
You should stop smoking.
You shouldn’t have done it!
SHOULD – affirmative and negative forms

+ SHOULD
MAIN VERB IN THE
BASE FORM
-SHOULD
NOT
- SHOULDN´T
+
COMPLEMENTS
SHOULD – interrogative form
SHOULD

MAIN VERB IN
THE BASE FORM
+
COMPLEMENTS
+
?
HAD BETTER
GIVE ADVICE
It is stronger than should and means that if the
person doesn’t follow the advice, s/he can
have negative consequences.
You had better not eat so much. The doctor told
you that you are overweight.
HAD BETTER – affirmative and negative forms

+
HAD BETTER
MAIN VERB
´D BETTER
IN THE BASE
FORM
-
+
HAD BETTER
NOT
COMPLEMENTS
ATTENTION!
´D BETTER
NOT
IT´S NOT OFTEN
USED IN THE
INTERROGATIVE
OUGHT TO
Advice or recommendations
Assumption or expectation
Strong probability(often with the idea
that something is deserved)
You ought to stop smoking.
Jim ought to get the promotion.
This stock ought to increase in value.
Mark ought not drink so much
OUGHT TO – affirmative and negative forms

+
Ought to
Main verb in
the base form
+
-
Ought not
complements
ATTENTION!
NOT USED IN
INTERROGATIVE
SHALL
SUGGESTION
Shall we go to the movies?
ONLY USED IN INTERROGATIVE AND
AFFIRMATIVE 1ST PERSON
SINGULAR AND PLURAL