This document provides information about modal verbs used for making deductions and expressing certainty, probability, and possibility. It discusses modal verbs like must, should, can't, may, might, could, will, and won't. Examples are given for how to use each modal verb to talk about certainty, probability, or possibility. The document concludes with an exercise asking the reader to complete sentences using the correct modal verb form.

1. MODAL VERBS FOR
DEDUCTIONS
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2. Modal verbs for certainty
 Certainty
She must be tired.
 Probability
-Where is Ann? - She should be at school right now.
 Possibility
We might go to Chile next month.
 Impossibility
It can’t be Josh, he is out of the city.

3. Modals
 Third person singular has no – S
She must be tired (NOT: she musts…)
 Questions and negations are formed without DO
You mustn’t go there! Should I? It cannot be true!
 After modals (except OUGHT) we use infinitives
without TO
I can’t swim (NOT: I can’t to swim)
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4. Modals + infinitives
 Modals can be
followed by
 PERFECT
 PROGRESSIVE
 and PASSIVE
infinitives
 You should have told
me earlier.
 I should be studying,
not playing with my
phone.
 They must be cured as
soon as possible.

5. MUST
 Use MUST when you are certain that something is
true:
 She must be in the house – her car is parked outside and
the lights are on.
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6. CAN’T
 Use CAN’T when you are certain that something is
not true:
 She can’t be in the house – I took her to the airport
yesterday and saw her getting on a plane to Russia.

7. SHOULD/SHOULDN’T
 Use SHOULD/SHOULDN’T when you are not sure
that something or not, but you think there is a good
possibility that you could be right:
 She should be home by now – she left her office an hour
ago.
 I can install this app myself – it shouldn’t be too difficult.

8. OUGHT TO/OUGHT NOT TO
 Has the same meaning as should and shouldn’t:
 I will ask my mom – she ought to know.
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9. WILL and WILL NOT/WON’T
 WILL has a similar meaning to MUST, and WON’T
has a similar meaning to CAN’T. We use WILL and
WON’T when we talk about normal, typical actions
which are expected:
 - There is someone at the door!
- That will be Mary, she always returns home at this time.
 - Let’s go and get something to it.
- No, the canteen won’t be open yet. Let’s go in an hour.

10. MAY/ MAY NOT
 Use MAY/MAY NOT to express possibility:
 We may go to Chile next year.
 She may not be at home (Perhaps, she is not at home)
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11. MIGHT and COULD
 Express a smaller probability:
 We might/could go to Chile next year, but I am not sure
we will.
possibility
100% - we will
0% - we won’t
we might/could
60% - may
NOTE:
1. We may go to the
cinema tonight. *There is a
chance that we will go to the
cinema*
2. We might go to the
cinema tonight *There is still a
chance that we will go, but the
probability is much less than in the
first sentence*

12. MIGHT and COULD
NOTE:
CAN is not normally used to talk about probability
She MAY be at home (NOT: She can be at home)
CAN shows one’s ability to do something:
I can swim, I can dance
and it can be replaced with I AM ABLE TO
CAN = I AM ABLE TO

13. Let’s practice
 Complete the sentences with the correct modal
either in the positive or negative form, sometimes
more than one option is possible
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14. Let’s practice
 1. Alejandra ______ be able to translate it for you
– she knows some Russian.
 2. Look at this luxurious house! They ____ have a lot
of money.
 3. Could you help me install this app? It ______
take long.
 4. - Someone is at the door? Do you think it _____
be Daniel?
 - No, it _____ be Daniel. He is out of the country.

15. Let’s practice
 5. Alina _____ still be at the office. She is always the
last one to leave.
 6. You have won a million dollars in a lottery??? It ____
be true!
 7. Our team ____ possibly win today’s match.
 8. Let’s hurry! We _____ still be able to catch the train!
 9. She _____ be his mother – they are almost the same
age.
 10. Lorena ______ be out of the hospital yet. Her
operation is scheduled for tomorrow.

16. Have Fun Learning 