Modal verbs of deduction behave differently to the other types of modal verbs

1. Modal verbs
of
deduction

2. can
can’t
will /
won’t
shall may must
could would should might -

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
will
may
might
won’t
can’t
be at home now.

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

11. Sally
must
will
may
might
won’t
can’t
be at home now.
I suppose

12. Sally
must
will
may
might
won’t
can’t
be at home now.
it’s possible

13. Sally
must
will
may
might
won’t
can’t
be at home now.
c.f. modal verbs
of possibility

14. Sally
must
will
may
might
won’t
can’t
be at home now.
I suppose she
isn’t

15. Sally
must
will
may
might
won’t
can’t
be at home now.
I’m sure she isn’t
(even if I don’t
know)

16. notice the opposites

17. Sally must be at home now.
Sally can’t be at home now.

18. Sally will be at home now.
Sally won’t be at home now.

19. modal verbs of deduction
have a continuous form

20. Something
must
will
may
might
won’t
can’t
be working.

21. use the continuous infinitive
after the modal

22. continuous infinitive
be working
be speaking
be thinking
etc.

23. N.B.

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

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

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

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

28. modal verbs of deduction
have a past form

29. Something
must
will
may
might
won’t
can’t
have worked.

30. use the perfect infinitive
after the modal

31. perfect infinitive
have worked
have spoken
have thought
etc.

32. N.B.

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

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

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

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

37. exercise

38. convert continuous modals
to perfect
and perfect modals
to continuous

39. 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 will be wearing the jacket.
They won’t 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 will be enjoying her holiday.

40. continuous modal perfect modal
She might be calling. She might have called.
They can’t be studying. They can’t have studied.
He must be going by bus. He must have gone by bus.
She won’t be cooking dinner. She won’t have cooked dinner.
He will be wearing the jacket. He will have worn the jacket.
They won’t be taking their exams. They won’t have taken their exams.
I must be dreaming it. I must have dreamt it.
They may be arguing. They may have argued.
He can’t be choosing. He can’t have chosen.
You must be paying a lot. You must have paid a lot.
She will be enjoying her holiday. She will have enjoyed her holiday.

41. may have done
vs.
might have done

42. 1. when we don’t know

43. They
may
might
have lost my letter.

44. They
may
might
have lost my letter.
it’s possible that
they have lost my
letter

45. They
may
might
have lost my letter.
‘may’ and ‘might’
mean the same

46. 2. result that didn’t happen

47. You might have killed yourself.

48. You might have killed yourself.
you didn’t kill
yourself, but you
did risk it

49. You might have killed yourself.
only ‘might’ is
possible

50. I might not have married her.

51. I might not have married her.
I married her but
if…

52. homework

53. module 7, parts 12, 13, 14

55. www.davidnicholson.it