Modal Verbs of Deduction

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 (last lesson)

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. www.davidnicholson.it