Deduction & Speculation Exercises PDFSet 5: Advanced Speculation: Must Have Been Doing & Complex Modal Deduction
20 questions·15 min·Answers included·Explanations included
Preview: Questions
Fill in the blank with the correct option.
1.When I got home at midnight, the kitchen was a mess — flour everywhere, dirty bowls in the sink, and the oven was still warm. Someone ___ all evening.
a) can't have been cookingb) might have bakedc) must have been bakingd) should have been cleaning
2.I heard some faint music coming from the flat upstairs last night, but I'm not entirely sure what it was. The neighbours ___ a small gathering.
a) could have been havingb) must have been havingc) can't have been havingd) should have been having
3.The report claims that Professor Harris was conducting experiments in the lab at 3 p.m., but the security log shows he left the building at 2:15 p.m. He ___ experiments at that time.
a) must have been conductingb) can't have been conductingc) might have been conductingd) may have been conducting
4.Given the severity of the storm last night and the age of the roof tiles, the leak ___ by the heavy rainfall.
a) must have causedb) can't have been causedc) shouldn't have been causedd) may well have been caused
5.Her eyes were red and puffy when she walked into the meeting. She ___ just before she arrived.
a) might have criedb) couldn't have been cryingc) must have been cryingd) should have been preparing
... and 15 more questions in the PDF
Preview: Answers
1.must have been baking
2.could have been having
3.can't have been conducting
4.may well have been caused
5.must have been crying
... and 15 more answers in the PDF
Preview: Explanations
1."must have been baking"(c)
Use 'must have been + -ing' when strong evidence points to an activity that was ongoing over a period in the past. Flour, dirty bowls, and a warm oven are strong evidence of prolonged baking. 'Might have baked' is too weak for this overwhelming evidence and doesn't capture the ongoing nature ('all evening'). 'Should have been cleaning' expresses obligation, not deduction.
2."could have been having"(a)
Use 'could have been + -ing' to speculate about a past ongoing activity when you are uncertain. 'I'm not entirely sure' signals uncertainty, so 'must have been having' (strong deduction) is too strong. 'Can't have been having' contradicts the evidence (there WAS music). 'Should have been having' expresses obligation.
3."can't have been conducting"(b)
Use 'can't have been + -ing' when concrete evidence proves that an ongoing past activity was impossible. The security log (he left at 2:15) directly contradicts the claim that he was conducting experiments at 3 p.m. Neither 'might' nor 'may' is appropriate when the evidence is conclusive.
4."may well have been caused"(d)
'May well have been caused' expresses a strengthened possibility — it's more than just 'may' but less certain than 'must'. The evidence (severe storm + old tiles) makes it likely but not certain, since other factors could be involved. 'Must have caused' is too strong and uses the wrong voice (active instead of passive). 'Can't have been caused' contradicts the evidence.
5."must have been crying"(c)
Use 'must have been + -ing' for a strong deduction about an activity that was ongoing shortly before a past moment. Red and puffy eyes are strong evidence of recent crying. 'Might have cried' is too weak for such clear evidence and doesn't capture the sense of an activity in progress just before arriving. 'Couldn't have been crying' contradicts the evidence.
... and 15 more explanations in the PDF
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