Past modals of deduction
must have + past participle for certain positive deductions; can't or couldn't have + past participle for certain negative deductions; might, could or may have + past participle for possible deductions; negative possibilities with may not or might not have; informal contractions with 've.
1. There is mud all over Theo's boots. He _____ through the fields.
Multiple Choice20sAmust have walked✓Bcan't have walkedCmay not walkDmust walk💡 The visible evidence supports a confident deduction about a completed past action.
2. Must have + past participle expresses a strong positive deduction about the past.
True / False20sTrue ✓False💡 Must have is used when the speaker feels certain that something happened or was true.
3. Nadia had no access to the account, so it was impossible for her to send the message: she _____ it.
Fill the Gap20sAcceptedcan't have sent · cannot have sent · couldn't have sent · could not have sent💡 Can't/couldn't have + past participle expresses a confident conclusion that a past action was impossible.
4. I cannot find the receipt. I _____ it in the taxi, but I am not sure.
Multiple Choice20sAmight have left✓Bmust have leaveCcan have leftDcouldn't leave💡 Might have + past participle presents a possible past explanation.
5. Match each piece of evidence to the most logical deduction.
Matching30sThe pavement is soaked.→It must have rained.Marta was abroad all week.→She can't have attended the meeting.The door was already open.→Someone may have arrived earlier.The instructions were unclear.→They might not have understood.Both routes were blocked.→He could have taken the train.💡 The modal perfect forms show certainty, impossibility or possibility based on evidence.
6. Use forget to make a certain positive deduction: Ravi looks surprised by the deadline. He _____ about it.
Fill the Gap20sAcceptedmust have forgotten💡 Must have forgotten is a strong deduction about an earlier event.
7. Put the chunks in order to make a possible explanation for their early arrival.
Put in Order30s- 1.They
- 2.might have taken
- 3.an earlier train
- 4.to avoid
- 5.the strike.
💡 Might have + past participle makes a possible deduction about the past.
8. Which form is not used for a possible past deduction?
Multiple Choice20sAcan have missed✓Bcould have missedCmay have missedDmight have missed💡 The reference allows could, may and might have, but not can have, for this meaning.
9. Could have + past participle always shows that the speaker is certain what happened.
True / False20sTrueFalse ✓💡 Could have normally presents a possible past event rather than a certain one.
10. The supplier _____ our revised order; that is one possible explanation for the delay.
Fill the Gap20sAcceptedmay not have received · might not have received💡 May not or might not have + past participle expresses an uncertain negative possibility.
11. The gallery was closed all day, so the noise _____ from inside it.
Multiple Choice20sAcan't have come✓Bmust have comeCcan have comeDmight come💡 Can't have + past participle gives a strong negative deduction from the evidence.
12. Match each modal-perfect form to its degree of certainty.
Matching30smust have happened→speaker is certain it happenedcan't have happened→speaker is certain it did not happenmight have happened→speaker thinks it was possiblemay not have happened→speaker thinks non-occurrence was possiblecould have happened→speaker sees one possible explanation💡 The choice of modal indicates how certain the speaker is about a past event.
13. Their repeated mistake makes this deduction almost certain: They _____ the address.
Fill the Gap20sAcceptedmust have misunderstood · must've misunderstood💡 Must have can contract to must've in speech and informal writing.
14. In a past modal of deduction, have is followed by a past participle.
True / False20sTrue ✓False💡 The core form is modal + have + past participle.
15. Which is the standard full form of 'She couldn't've known'?
Multiple Choice20sAShe couldn't have known.✓BShe couldn't had known.CShe couldn't have know.DShe didn't could have known.💡 The full structure is couldn't + have + past participle.
16. Reorder the chunks to make a possible explanation for the missing parcel.
Put in Order30s- 1.The courier
- 2.could have delivered
- 3.the parcel
- 4.to our neighbour
- 5.by mistake.
💡 Could have + past participle expresses one possible explanation.
17. There were fresh puddles everywhere, so it _____ during the night.
Fill the Gap20sAcceptedmust have rained💡 Must have rained is a confident deduction based on present evidence.
18. Ben has not replied. Which sentence presents forgetting as only a possibility?
Multiple Choice20sAHe may have forgotten.✓BHe must have forgotten.CHe can't have forgotten.DHe can have forgotten.💡 May have signals possibility rather than certainty.
19. The correct form is 'They might have went home early.'
True / False20sTrueFalse ✓💡 Have must be followed by the past participle gone, not the past simple went.
20. Leo was on another continent that day, so he _____ the local briefing.
Fill the Gap20sAcceptedcan't have attended · cannot have attended · couldn't have attended · could not have attended💡 Can't/couldn't have + past participle expresses a certain negative deduction.