This document discusses the use of modal verbs to express different degrees of certainty in English, including speculation about present, past, and future events. It explains that modals followed by base verb forms are used for present and future speculation, while past speculation uses modals followed by past participle verbs. Modals like must, have to, should express near certainty, couldn't and can't express near impossibility, and may, might, could express less certainty. Examples are provided to illustrate speculating about reasons for classroom situations, the futures of present technologies, and more.

1. 2
Modals to Express
Degrees of Certainty
Nosy Neighbors
Focus on Grammar 5
Part II, Unit 6
By Ruth Luman, Gabriele Steiner, and BJ Wells
Copyright © 2006. Pearson Education, Inc. All rights reserved.

2. Nosy Neighbors 1
Nosy Neighbors 1
Honey, how can
Mrs. Carson afford
a Ferrari? Isn’t she
a teacher?
I suppose. Or she
could have won
the lottery.
I doubt it. She
had to have
robbed a bank!
Well, she might
have inherited
some money from
her knows?
Who family.
She may have
gotten a big
raise at work.
You could
be right.

3. Nosy Neighbors 2
Nosy Neighbors 2
I haven’t
seen the
Chins for a
They may
month.
have been
abducted by
Hmmm. They
aliens.
must have
moved to an
exotic island.
Well, they
couldn’t have
gone on
vacation. The
Or they
dog is still there.
might be
staying with
their son for a
Then they
while.
should be
very happy.

4. Speculating about the Present
Speculating about the Present
Modals speculating about the present are
followed by a base form verb.
You could be right.
base form verb
Then they should be very happy.

5. Speculating about the Past
Speculating about the Past
Modals speculating about the past are
followed by the past participle.
She could have won the lottery.
past
participle
She may have gotten a big raise.

6. Review
Review
Modals and modal-like expressions express
degrees of certainty.
Degree of Certainty
certain
near
certainty
near
less
impossibility certain
no
modal
must
have to
have got to
can’t
couldn’t
may
might
could

7. Certainty
Certainty
Modals and modal-like expressions express degrees
of certainty. Don’t use a modal for 100% certainty.
The Chins went on vacation.
Mrs. Carson got a raise.

8. Near Certainty
Near Certainty
There are several modals that express near certainty,
including must have and had to have.
They must have moved to
an exotic island.
He had to have robbed a
bank.

9. Near Impossibility
Near Impossibility
There are several modals that express near certainty
that something is impossible, including couldn’t have
and can’t.
They couldn’t have moved away.
They just
moved here.
They can’t be out of town.
They left all the
lights on!

10. Less Certainty
Less Certainty
There are several modals that express less certainty,
including may, and might.
They may have been abducted
by aliens.
They might be staying with
their son.

11. Practice 1
Example:
Use modals to suggest reasons for
these classroom situations. Speculate
on what might have happened.
One of your classmates is late.
She must have gotten stuck in traffic.
There was a big accident.
1. You smell smoke.
2. The teacher is angry.
3. The desks are shaking.
4. You can’t find your textbook.
5. The lights go out.

12. Speculating about the Future 1
Speculating about the Future 1
Modals speculating about the future are also followed
by a base form verb. The modals should and ought
to express near certainty.
That Ferrari should last a lifetime.
She ought to take us for a drive soon.

13. Speculating about the Future 2
Speculating about the Future 2
Use may, might, and could when you are
less certain.
The Chins may not return.
The house might get sold.
They could move next month.

14. Practice 2
Use modals to express future
possibilities about these
present situations.
Example: We shop for food at grocery stores.
‘Smart’ kitchens might calculate what we need and
order it electronically. In the future, household
computers may do all our shopping.
1. Ordinary people don’t travel in space.
2. Houses are made of wood.
3. People pay for products with cash or credit cards.
4. Our fingerprints provide identification.

15. References
References
Copyright © 2006 Pearson Education and
its licensors. All rights reserved.