The use of the modal verbs (might/may, must, can't/couldn't) for speculation and deduction. Also, how to use "should/ought to" to express regret and criticism

1. Past modals
MíriamTomàs

2. Logical assumptions and
deductions

3. How can we express certainty,
probability or speculation?
Let’s put on
the thinking
cap

4. must
You have been practising all day,
you must be exhausted!

5. must
Sean and Jennie must be going out again. I’ve seen
them talking very lovey-dovey, you know.

6. Logical assumptions and deductions
Must:
▪ is used in affirmative sentences.
▪ states something about which you are certain that is true.

7. Modal verbs and different tenses
We can use modal
verbs with different
combinations of
verbs to change the
time of the actions.

8. must
You have been practising all day,
you must be exhausted!

9. must
You have been practising all day,
you must be exhausted!
Infinitive = present
speculation

10. must
Sean and Jennie must be going out again. I’ve seen
them talking very lovey-dovey, you know.

11. Infinitive + gerund (continuous) = in
progress at the time of speaking
must
Sean and Jennie must be going out again. I’ve seen
them talking very lovey-dovey, you know.

12. must
I must have left my phone at Anna’s.
I definitely remember having it there.

13. must
I must have left my phone at Anna’s.
I definitely remember having it there.
Have + past participle =
speculation about the past

14. Next!

15. Can’t and couldn’t
What you say about Claire and Jake can’t be true!They’re so
good together it’s impossible they’re going to break up.

16. Someone’s been at home, but it can’t have been James, he
was at work.
Can’t and couldn’t

17. You couldn’t have seen their faces. It was too dark.
Can’t and couldn’t
Couldn’t = when the speculation is
about the distant past

18. Can’t and couldn’t
▪ Can’t and couldn’t are used in negations and express negative
logical assumptions.That is to say, you use them when you’re
certain that something is not true or real.
Monsters can’t be real!

19. Can’t and couldn’t
▪ Can’t and couldn’t are the opposite of must. So we
don’t say:
Monsters mustn’t be real!
but:
Monsters can’t be real!

20. Infinitive = speculation about
the present
Can’t and couldn’t
What you say about Claire and Jake can’t be true!They’re so
good together it’s impossible they’re going to break up.

21. Someone’s been at home, but it can’t have been James, he
was at work.
Can’t and couldn’t
Have + past participle =
speculation about the past

22. The children can’t be studying. I can hear them
gossiping.
Can’t and couldn’t
Infinitive + gerund = speculation
about an action in progress at the
time of speaking

23. Possibility and probability

24. They might have been a perfect match, but something
got in their way.
May and might

25. Someone might have stolen your wallet when you got
off the train.
May and might

26. He hasn’t arrived yet. I may have given him the wrong
directions.
May and might

27. We use may and might when we think it’s possible that
something’s happened or is true.
May and might
We’re not 100% sure!

28. He hasn’t arrived yet. I may have given him the wrong
directions.
He might be lost.
He might be looking for the right directions.
May and might
Different tenses can also be
used:
Infinitive  present
Have + past part.  past
Infinitive + gerund  action
in progress

29. Regret & criticism

30. You ought to have fed the
cat and dog.

31. It’s my fault. I should have
told you earlier my mother
was coming.

32. Should and ought to
▪ Should have + past participle is used to criticise someone’s
actions or lack of them in the past, or in other words to say that
somebody didn’t do the right thing in the past.
Ought to have + past
participle is used as
an alternative to
should

33. Now it’s your
turn!
Go to page 156 to complete
exercise 3.