Bài giảng modal verbs

VERBS

Main contents:
I.
II.
III.
IV.
V.

Definition of modal verbs
Characteristics
Form
Usage
Exercise and recap


I. DEFINITION:
Modal verbs ( or Modal auxiliary verbs) are special
verbs such as:
Can

Shall

Could

Should

Will

May

Would

Might
Must

They are used with another verb to express an idea such
as possibility, necessity... that are not expressed by the
main verb of a sentence.


II. CHARACTERISTICS
- All modal verbs have some special characteristic you
should remember :


EXAMPLE:

Mary can play the guitar quite
well.


1. They are always followed by an infinitive
without “to”.
2. They never change their form for all subjects.
Modal verbs don’t take “-s” in the third person
singular.
You cannot say: she/he wills or she/he cans

3. Like the other auxiliary verbs (be, have and
do) in negatives, questions, tags and so on.
- Use “not/n’t” to make modal verbs negative.
E.g: I cannot/can’t speak english.
- It comes before the subject in questions.
E.g: Can you speak English?
.


4. Many modal verbs cannot be used in the past tenses
or the future tenses.
E.g:
He will can go with us. Not Correct
She musted study very hard. Not Correct

Some different expressions:
-Be able to
-Be allowed to
-Have (got) to



III. FORM:

(+) S+ modal verbs+ bare infinitive.
 E.g:


(-) S+ modal verbs+ not+ bare infinitive.

 E.g: You must not/ mustn’t smoke here.


(?) Modal verbs+ S+ bare infinitive?


E.g:

Should I phone
her and
apologize?


IV. USAGE:
ABILITY

CAN/COULD

PERMISSION

CAN/COULD/MAY

POSSIBILITY

CAN/COULD/MAY/MIGHT

OBLIGATION

MUST

PROHIBITION

MUSTN’T/ CAN’T

LACK OF NECESSITY

NEEDN’T/ DON’T NEED TO/ …

ADVICE

SHOULD/OUGHT TO/HAD BETTER

SUGGESTION, OFFER AND
INVITATION

SHALL/CAN/COULD/WILL/WOULD

HABITS

WILL/WOULD


1. Modal of ability:
- To talk about someone's
skill, power or physical
ability to do something.

what is
ability?
Past

Could

Present Future
Can

Can


Can:
-we use to say that somebody has ability to do
something at a given time in the present/ future.
E.g: She can speak several languages.
She is thinking of all the things she can buy.
-We can say that somebody is able to do some
thing.
E.g: She is able to speak several languages.
 Can is more usual.
 Be able to is more formal.



Could
- General ability in the past.
E.g: Jack was an excellent tennis player, he could
beat anybody.
-We use Could especially with: see/hear/smell…
E.g: John spoke in a soft voice but I could hear
what he said.
 Were/was able to
- Special ability in the past.

E.g: Jack and john played a match yesterday and
john was able to beat Jack.



Could+ have+ PII
- To talk about someone had
ability/opportunity to do something, but they
didn’t do it.
E.g: - John could have played the piano well
but he didn’t practice enough.



2. Modal of Permission.
(Can/ Could/ May)
To ask for permission to do something.
E.g: - Can I use your phone?
- May I come in?
- Could I borrow your car?
 Can: informal.
 Could and may is more formal and a good
way of asking for permission.


To give permission
- We use: can/may.
E.g: -You can/may wait for her in her office
if you like.
 To say that people has permission to do

something:
E.g: You can go out whenever we want.
Students may travel free.
 We also use modal verbs in negative to
say that something is not allowed.
E.g:
can’tand
drive
a car.
MayIfisyou
not under
only a 18,
moreyou
formal
polite
way


of giving permission, but also saying that
someone has permission to do something.


3. Modal of Advice
Should:
- To say that it is a good thing to do or the
right thing to do.
E.g: - You look tired. You should visit a doctor.
 Shouldn’t:
- To say that it isn’t a good thing to do.
E.g: You shouldn’t believe everything you read

in the newspapers.



Should
to be+
- We
alsobe/
useought
Ought
to/ V-ing
had better to express the
- same
To saymeaning.
that you expect something to happen but it
is
not
right.
• Ought to is less common in the speech
7 o’clock. You should be preparing for
• E.g:
Had-It’s
better:
usually implies a warning or a
dinner.
threat of possible bad consequences.
 Should (not) +have+ PII.
E.g: You had better not be late, or I will be
- To express the idea that something was desirable or
furious!

needed but didn’t take place.
E.g: I should have called you yesterday but I forgot.


4. Modal of Obligation.
-To say that it is necessary or unnecessary to do
something.
E.g: I must obey my parents.
- Students have to wear uniforms at school.
Note: the difference between Must and have to:
Must:

to talk the obligation comes from inside the
speaker.
Have/has to: to talk about the obligation comes
from outside. It is usually referring a rule, or law.


5. Prohibitions
- We use: “Mustn’t/ can’t” to show that
something is prohibited (not allowed).
E.g: You mustn’t use phone in class.
You can’t drive a car in this country unless
you are over 18.
 Can’t: usually gives the idea of something that
is against the rules.
 Mustn’t: usually means that it is the speaker
who is setting the rules.

6. Lack of Necessity.
- To say that is unnecessary to do something.
 Lack of necessity in the present.
have
I don’t need
I

needn’t

to take my umbrella. It is
not raining.
take my umbrella. It is not
raining.


6. Lack of Necessity.
- To talk that is unnecessary to do something.
 Lack of necessity in the past.
Didn’t need have
to= Didn’t have
to myNeedn’t
have+ItPII
To take
umbrella.
was not
ToI didn’t
talk aboutneed
the action was
Toraining.
talk about the action

not necessary to do and person was unnecessary and even
didn’t do it.
a waste of time but it was
alreadymy
done.
I
Needn’t Have taken
umbrella. It

was not raining.


How certain you are about present situation.

7. Modals of Probability and Possibility.
Modals
Degree of certainty
Example
- To make
guess
about something
(that
Must
Abouta 90%
certain.
You haven’t
eaten all day.
something
happening/will

You must be hungry.
-We are happened/is
sure that something
to behappen)
true and we have
possible
reasons for our belief.

Can’t/
- To show that you strongly
Couldn’t believe that something is
impossible.

That’s impossible! John
couldn’t be in Las Vegas. I
saw him just a few minutes
ago. He can’t be here.

May
Might
Could

-situation: Mary is
wearing a white coat.
She could/might/may be a
doctor.

- Less than 50% certain
- To express possibility (to
show that you believe

something is possible, but
you are not very certain)