The document explains modal verbs that express necessity or obligation, including 'must,' 'have to,' 'should,' and their negative forms. It outlines their uses in present and past contexts, distinguishing between strong obligation, mild obligation, and prohibition. Additionally, it provides a writing prompt encouraging the development of desirable traits while discouraging negative habits.

1. (Modals that express necessity or
obligation)

2. Read the following statements:
1. I need to pay the bills.
2. I must accomplish the reports.
3. The king ought to know more
about his enemies.

3. Modal Verbs of Obligation
Remember the following points.
Modals are auxiliary verbs performing specific
functions. Some examples are:
•Must – express obligation
•Need to – indicates necessity
•Should and ought to – express sense of
obligation to do, or to become something
•Shouldn’t and should not have, or ought not –
indicate prohibition, or disapproval of
something that was done in the past.

4. Modal Verbs of Obligation
To express obligation (something
you have to do), we can use the
following:
a.have to + base of the verb
b.must + base of the verb
c.should + base of the verb

5. Modal Verbs of Obligation
Present Positive Negative
have to /
don't have
to
strong
obligation
(possibly from
outside)
Children have to
go to school.
(sometimes
'have got to')
no obligation
I don't have to
work on
Sundays.
You don't have
to eat anything
you don't like.

6. Modal Verbs of Obligation
Present Positive Negative
must /
mustn't
strong
obligation
(possibly
based on the
speaker's
opinion)
I must study
today.
negative
obligation
You mustn't
smoke here.

7. Modal Verbs of Obligation
Present Positive Negative
should /
shouldn't
mild obligation
or advice
You should
save some
money.
mild negative
obligation or
advice
You shouldn't
smoke so
much.

8. Modal Verbs of Obligation
Be careful about the difference
between mustn't and don't have to!
- Mustn't means it's not allowed, or
it's a bad idea:
You mustn't eat so much chocolate,
you'll be sick
- Don't have to means you don't need to do
something, but it's fine if you want to do
it:
I don't have to get up early at the weekend(of
course, if I want to get up early, that's fine, but
I can stay in bed if I want).

9. Modal Verbs of Obligation
Past Positive Negative
had to / didn't
have to
should have + pp
/ shouldn't have
+ pp
obligation in the past
•I had to wear a
school uniform when I
was a child.
a past action which
didn't happen: the
advice / regret is too
late
•You should have
gone to bed earlier,
now you have missed
the train.
no obligation in the
past
•We didn't have to
go to school on
Saturdays.
a past action which
didn't happen: the
advice / regret is too
late
•You shouldn't have
taken that job, it
was a bad idea.

10. Modal Verbs of Obligation
•Write at least five desirable traits or habits you
need to develop, and five habits you ought to
weed out.
•Write a short paragraph persuading others on the
importance of developing these desirable
attitudes and weeding out the undesirable habits
to win over challenges. Use this title: “Habits and
Traits to Develop or to Weed Out in Order to Win
over Challenges.” Clarify your stand and use words
that appeal to reason or emotion. Remember to
use the appropriate modals.