2. What are modal verbs?
A modal is a type of auxiliary (helping) verb that is used to express:
ability, possibility, permission or obligation. Modal phrases (or semi-
modals) are used to express the same things as modals, but are a
combination of auxiliary verbs and the preposition to. The modals and
semi-modals in English are:
Can/could/be able to
May/might
Shall/should
Must/have to
Will/would
3. SHOULD
• used for giving or asking for advice
I am feeling sick. What should I do?
You should go see a doctor.
• used to show what is right, appropriate, etc.,
especially when criticizing somebody’s actions
You shouldn’t drink alcohol.
You should study for the exams.
4. • Used to say that you expect something is true or
will happen
We should arrive before dark.
I should have finished the book by Friday.
The roads should be less crowded today.
• Used to say that something that was expected has
not happened
It should be snowing now, according to the weather
forecast.
The bus should have arrived ten minutes ago.
5. STRUCTURE
Affirmative
Subject + modal verb + verb + compl.
Erica should wake up early tomorrow because she has a
test.
Negative
Subject + modal verb + not + verb + compl.
Manuel should not drive too fast since he could have an
accident.
( Shouldn’t )
7. EXAMPLES
Jake should study more for his coming exams.
Jacob shouldn’t stay up until too late.
Jessica shouldn’t watch too much T.V.
Should I study on vacations?
Marvin should read more books.
8. Have to & must
Have to is NOT an auxiliary verb (it uses the
verb have as a main verb). We include have to here
for convenience.
Must is a modal auxiliary verb.
9. USE OF HAVE TO
In general, have to expresses impersonal obligation. The subject of have
tois obliged or forced to act by a separate, external power (for example,
the Law or school rules). Have to is objective. Look at these examples:
In France, you have to drive on the right.
In England, most schoolchildren have to wear a uniform.
John has to wear a tie at work.
In each of the above cases, the obligation is not the subject's opinion or
idea. The obligation comes from outside.
We can use have to in all tenses, and also with modal auxiliaries. We
conjugate it just like any other main verb.
12. USE OF MUST
Must expresses personal obligation. Must expresses what the speaker thinks is
necessary. Must is subjective. Look at these examples:
o I must stop smoking.
o You must visit us soon.
o He must work harder.
In each of the above cases, the "obligation" is the opinion or idea of the person
speaking. In fact, it is not a real obligation. It is not imposed from outside.
13. We can use must to talk about the present or
the future. Look at these examples:
I must go now. (present)
I must call my mother tomorrow. (future)
We cannot use must to talk about the past. We
use have to to talk about the past.
