Wednesday 4 April 2018

Modal Verbs: Ability. Advice, Necessity and Obligation. Possibility and Certainty.


Hi, everyone! We're going to revise the form and use of modal verbs.

Form.

The first thing we have to know is the type of modal verbs there are:
Pure modals
Semi-modals
can
be able to
could
may
have better
might
must
have to
shall

should

ought to

will

would

need ***
need to
*** need is a special verb since as a modal it is almost always negative such as you needn't come to work tomorrow
The pure modals are used just exactly as the auxiliary verbs in the sentence word order.
Subject
Modal / Auxiliary
Verb
Object
Manner, place and time
You
shouldn't
be
so stressed
for driving
You
needn't
drive

to school
I
can
give
you
a lift


Their main difference is that pure modals are invariable forms, that is, we can't use them in the past or future forms.
Instead, the semi-modals can be used in the past, future and the rest of tenses too.

Use.

For understanding the meaning and use of the modal verbs we can establish different uses: ability; advice, necessity, and obligation; possibility and certainty.

Ability

We express ability by means of the modals can and could and the semi-modal be able to.
Here a presentation to learn more about the modals of ability:

Exercises:

Advice, necessity, and obligation

For expressing advice we have the modals:
  • should and ought to (ought to isn't usually used in the negative and interrogative form) to express advice.
  • need to to express necessity (only in the affirmative form).
  • needn't (without to) and the don't/doesn't have to are used to make clear there's no need to do something.
  • must and have to express obligation.
  • mustn't for expressing prohibition (obligation of not doing)
For more information, you can watch these presentations
  • Advice

Exercises:
  • Necessity

Exercises:


  • Obligation


Exercises.

Possibility and certainty

The modal verbs we use to express possibility and certainty are may, might, can, could, must
  • to express possibility in the present or the future we may (may not), might (mightn't) and could.
  • To express logical deduction we use must (in the affirmative form) or can't (in the negative form).
  • When we are sure something is true we use must.
  • When we are sure something is impossible we use can't.

Exercises: