Expressing Certainty, Possibility, and Advisability in the Past Using Modals + Perfective

In English Dialogue: Expressing Past Probability With Modals + Perfective, you have noticed the use of modals + perfective in English conversation. Let's take another look at the following sentences:

• I must have forgotten to take my umbrella.
• I might have lost it anywhere.
• How could you have lost it?
• I may have left it in the coffee lounge.
• You should have been more careful.

Do you understand what the above sentences mean? Do you know how to make a sentence with similar structure to those? Let's learn more about it here.

1. The Structure of Modals + Perfective

1. Affirmative / positive sentence:

Subject	Modals	have	past participle
I We You They He She It Etc.	may might ought to must could should	have	been slept arrived finished forgotten left gone Etc.

2. Interrogative sentence / question:

Question words	Modals	Subject	have	past participle
Who What How Where When Etc.	may might must could should	I we you they he she it Etc.	have	been? slept? arrived? finished? forgotten? left? gone? Etc.

3. Negative sentence:

Subject	Modals + not	have	past participle
I We You They He She It Etc.	may not might not ought not to must not (mustn't) could not (couldn't) should not (shouldn't) needn't	have	been slept arrived finished forgotten left gone Etc.

2. The Uses of Modals + Perfective

• May have past participle expresses less than 50% certainty.
  Example: I may have left my umbrella in the coffee lounge.
• Might have past participle expresses less than 50% certainty.
  Example: I might have lost it anywhere.
• Ought to have past participle expresses:
  • advisability
    Example: You ought to have talked to your manager, but you didn't.
  • 90% certainty/expectation
    Example: She ought to have done well in the test because she was well prepared.
• Must have past participle expresses 95% certainty/logical conclusion
  Example: You must have lost your umbrella, not your briefcase.
• Could have past participle expresses:
  • less than 50% certainty
    Example: I suppose someone could have picked it up before I rang.
  • unfulfilled suggestion (positive sentence only)
    Example: You could have talked to me before making the decision.
  • impossibility (negative only)
    Example: He couldn't have done such a silly thing.
• Should have past participle expresses:
  • advisability/unfulfilled expectation
    Example: He should have worked harder for the test, but he didn't.
  • 90% certainty/expectation
    Example: She should have done well in the test because she was well prepared.
• Needn't have past participle expresses lack of necessity.
  Example: You needn't have worried all day.

3. The examples of Modals + Perfective in dialogues

Practice this dialogue and pay attention to what modal + perfective structures imply.

Barbara: Yesterday I walked home from work, because I had no money for the bus.
Bill: You needn't have walked home yesterday. I could have lent you some money.
Barbara: I didn't like to borrow money from you.
Bill: Oh, but you should have asked me.

1. Choose the best answer to complete the dialogues.

1. Tom: Where was Mary yesterday? She wasn't at work.
   Bob: She ... sick yesterday.
   1. must have been
   2. needn't have been
2. Lucy: Betty isn't home.
   Ann: She ... to the shops.
   1. may have gone
   2. needn't have gone
3. Andy: Bob hasn't arrived yet.
   Bill: He ... in a traffic jam at this busy hour.
   1. ought to have been caught
   2. could have been caught
4. Lisa: I didn't know that the meeting would be postponed to next week.
   Mary: Yes. You ... the room today.
   1. might not have prepared
   2. needn't have prepared
5. Hadi: I think I've lost my key. I put it in my pocket after locking the room.
   Mary: You ... it anywhere.
   1. must have dropped
   2. should have dropped
6. Betty: He hasn't arrived yet. I assume he's lost his way.
   Rosa: I think so. He ... his way.
   1. must have lost
   2. needn't have lost
7. Jim: Nancy hasn't received the email.
   Bill: Really? It ... to the wrong address.
   1. ought to have gone
   2. may have gone
8. Dave: Bella didn't call her office when she was away from work yesterday.
   Gary: That was bad. She ... her boss.
   1. must have informed
   2. should have informed
9. Sam: I worked until late last night.
   Greg: You ... so hard. The report is due next week.
   1. could have worked
   2. needn't have worked
10. Rea: Did she phone the police?
    Lori: No. She ..., but she didn't.
    1. must have phoned
    2. could have phoned

2. Change the verbs

Change the verbs in he following sentences to indicate past time by using modal + perfective (modal + have + past participle). Number 1 has been done as an example.

1. That must be a very interesting play.
   That must have been a very interesting play.
2. Joan may not remember the number.
3. John might forget to do the shopping.
4. He needn't do that job.
5. You could borrow my laptop.
6. She should get to work on time.
7. They ought to tell me.
8. You needn't shout so loudly.
9. He should knock at the door before coming in.
10. She may know the answer.

^{Prev: BSE SMK Kelas XII, 7/3/11, 10:34 AM, PV 2042}