Modals 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.!