The document discusses modal verbs of deduction such as may, might, could, must, and can't. These modal verbs are used to express uncertainty or likelihood, rather than known facts. The choice of modal verb indicates the degree of certainty or possibility. For example, "must" implies more certainty than "may." Modal verbs of deduction can take continuous ("be + verb+ing") or perfect ("have + past participle") forms to express actions or states that are ongoing or completed. However, not all meanings of modal verbs allow the continuous or perfect form. The document provides examples and exercises to illustrate the use of modal verbs of deduction.

1. Modal verbs
of
deduction

2. can! !!
may!
might!
could!
couldn’t!!
+ be

3. Is Sally at home now?!

4. we use indicative tenses
to say what we know!

5. Sally is at home now.!
I know!

6. we use modals when we
suppose, deduce, imagine!

7. Sally must be at home now.!
I suppose!

8. the choice of modal verb says
how certain we are!

9. Sally!
Must!
may!
Might!
can’t!
be at home now.!

10. Sally!
must!
May!
might!
can’t!
be at home now.!
I’m convinced
(even if I don’t
know)!

11. Sally!
Must!
may!
Might!
can’t!
be at home now.!
it’s possible!

12. Sally!
Must!
may!
Might!
can’t!
be at home now.!
I’m sure she isn’t!
(even if I don’t
know)!

13. notice the opposites!

14. Sally must be at home now.
Sally can’t be at home now.!

15. modal verbs of deduction
have a continuous form!

16. Something!
Must!
may!
Might!
can’t!
be working.!

17. use the continuous infinitive
after the modal!

18. continuous infinitive
be working
be speaking
be thinking
etc.!

19. N.B.!

20. other meanings of the modals
don’t use the continuous
infinitive!

21. e.g.
He can’t speak French.
He can’t be speaking in French.!

22. e.g.
He can’t speak French.
He can’t be speaking in French.!
he doesn’t
know how!

23. e.g.
He can’t speak French.
He can’t be speaking in French.!
I don’t believe
he’s doing it!

24. modal verbs of deduction
have a past form!

25. Something!
Must!
may!
Might!
can’t!
have worked.!

26. use the perfect infinitive
after the modal!

27. perfect infinitive
have worked
have spoken
have thought
etc.!

28. N.B.!

29. other meanings of the modals
don’t use the perfect infinitive!

30. e.g.
He couldn’t speak French.
He can’t have spoken in French.!

31. e.g.
He couldn’t speak French.
He can’t have spoken in French.!
he didn’t know how!
when he was
younger!

32. e.g.
He couldn’t speak French.
He can’t have spoken in French.!
I don’t believe he
spoke in French!

33. exercise!

34. convert continuous modals
to perfect
and perfect modals
to continuous!

35. continuous modal! perfect modal!
She might be calling.!
They can’t have studied.!
He must be going by bus.!
She won’t have cooked dinner.!
He can’t be wearing the jacket.!
They must have taken their exams.!
I must be dreaming it.!
They may have argued.!
He can’t be choosing.!
You must have paid a lot.!
She must be enjoying her holiday.!