1. EXPRESSING DEGREES OF CERTAINTY: PRESENT TIME
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2. Why isn’t John in class?
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3. 100% sure: He is sick.
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4. 95% sure: He must be sick.
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5. Less than50% sure: He may be sick. He might be sick. He could be sick.
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6. Why isn’t John in class?
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7. He must be sick. (Usually he is in class every day, but when I saw him last night, he wasn’t feeling good.
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8. So my best guess is that he is sick today
So my best guess is that he is sick today. I can’t think of another possibility.)
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9. Why isn’t John in class?
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10. He may be sick. He might be sick.
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11. He could be sick. (I don’t really know. He may be at home watching TV
He could be sick. (I don’t really know. He may be at home watching TV. He might be at the library. He could be out of town.)
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12. Maybe he is sick. He may be sick.
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13. DEGREES OF CERTAINTY: PRESENT TIME NEGATIVE
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14. 100% sure: Sam isn’t hungry.
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15. 99% sure: Sam couldn’t be hungry. Sam can’t be hungry.
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16. 95% sure: Sam must not be hungry.
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17. less than 50% sure: Sam may not be hungry. Sam might not be hungry.
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18. Sam doesn’t want anything to eat. He isn’t hungry
Sam doesn’t want anything to eat. He isn’t hungry. He told me his stomach is full. He says he isn’t hungry. I believe him.
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19. Sam couldn’t / can’t be hungry. That’s impossible
Sam couldn’t / can’t be hungry! That’s impossible! I just saw him eat a huge meal.
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20. He has already eaten enough to fill two grown men
He has already eaten enough to fill two grown men. Did he really say he’d like something to eat? I don’t believe it.
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21. Sam isn’t eating his food. He must not be hungry
Sam isn’t eating his food. He must not be hungry. That’s the only reason I can think of.
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22. I don’t know why Sam isn’t eating his food
I don’t know why Sam isn’t eating his food. He may / might not be hungry right now.
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23. Or maybe he doesn’t feel well
Or maybe he doesn’t feel well. Or perhaps he ate just before he got here. Who knows?
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24. DEGREES OF CERTAINTY: PAST TIME
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25. Past Time: Affirmative
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26. Why wasn’t Mary in class?
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27. 100% She was sick.
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28. 95% She must have been sick.
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29. Less than 50%. She may have been sick. She might have been sick
Less than 50% She may have been sick She might have been sick She could have been sick.
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30. Past Time: Negative
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31. 100% Sam wasn’t hungry.
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32. 99% Sam couldn’t have been hungry. Sam can’t have been hungry.
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33. 95% Sam must not have been hungry.
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34. Less than 50%. Sam may not have been hungry
Less than 50% Sam may not have been hungry Sam might not have been hungry.
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35. DEGREES OF CERTAINTY: FUTURE TIME
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36. 100% sure: Kay will do well on the test. -(The speaker feels sure.)
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37. 90% sure: She should do well on the test. -(The speaker is almost sure.)
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38. She ought to do well on the test.
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39. less than 50% sure:. She may do well on the test
less than 50% sure: She may do well on the test. -(The speaker is guessing.)
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40. She might do well on the test.
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41. She could do well on the test.
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42. Kay has been studying hard
Kay has been studying hard. She should do / ought to do well on the test tomorrow.
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43. I wonder why Sue hasn’t written us
I wonder why Sue hasn’t written us. We should have heard / ought to have heard from her last week.
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44. PROGRESSIVE FORMS OF MODALS
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45. Let’s just knock on the door lightly. Tom may be sleeping. (right now)
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46. All of the lights in Ann’s room are turned off. She must be sleeping
All of the lights in Ann’s room are turned off. She must be sleeping. (right now)
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47. Sue wasn’t at home last night when we went to visit her
Sue wasn’t at home last night when we went to visit her. She might have been studying at the library.
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48. Al wasn’t at home last night
Al wasn’t at home last night. He has a lot of exams coming up soon, and he is also working on a term paper.
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49. He must have been studying at the library.
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