Grammar Time: Present and Past Modal Verbs of Deduction

Let’s focus on using modal verbs of deduction.

Exam in Mind Level B1+/B2

Use Modal Verbs of Deduction

  • must (present) and must have (past) when you are very certain that something is/was true
  • can’t (present) and couldn’t have (past) when you are very certain that something is/was impossible
  • should/shouldn’t (present) and should have / shouldn’t have (past) to talk about things you expect to be true, although you don’t have complete certainty; you can also use should have / shouldn’t have for judging actions in the past to be good or bad

Have practice in using modal verbs for deduction.

Task 1. Choose one of the following to complete the sentences:

  • must have 
  • might have
  • could have
  • may have
  • should have
  • can’t have
  1. John ____________ gone on holiday. I saw him this morning downtown.
  2. Nobody answered the phone at the clinic. It ____________ closed early.
  3. I ____________ revised more for my exams. I think I’ll fail!
  4. Sarah looks really pleased with herself. She ____________ passed her driving test this morning.
  5. I didn’t know you were going to Phil’s party yesterday. You ____________ told me!
  6. I can’t believe Jim hasn’t arrived yet. He ____________ caught the wrong train.
  7. I can’t believe Jim hasn’t arrived yet. He ____________ caught the correct train.
  8. Don’t lie to me that you were ill yesterday. You ____________ been ill – Don said you were at the ice hockey match last night.
  9. I don’t know where they went on holiday but they bought Euros before they left so they ____________ gone to France or Germany.
  10. His number was busy all night – he ____________ been on the phone continuously for hours.
  11. It ____________ been Mickey I saw at the party. He didn’t recognise me at all.

Task 2. Complete the blanks with must, can’t, or might:

  1. Look at that guy’s enormous muscles. He ________________ work out a lot.
  2. Michelle ________________ want to participate in the festival – it seems like the type of thing she’d be interested in. Why don’t you ask her?
  3. She goes camping every weekend. She ________________ really love the outdoors.
  4. He worked hard on his report, then accidentally deleted the file from his computer. He ________________ be upset.
  5. You ________________ be right – but I’m going to check to make sure.
  6. We’re not sure if this painting is an original. It ________________ be worth thousands of dollars.
  7. I ________________ not be able to go to the football game. It depends on whether I can get the afternoon off from work.
  8. He’s working full-time and studying for his Ph.D. That ________________ be easy.
  9. You just ate a huge dinner! You ________________ be hungry again already!
  10. Wow – look at that diamond necklace. It ________________ cost a fortune!

Task 3. Complete the blanks with must, should, shouldn’t, or couldn’t:

  1. I’m so thankful for your help with this project. I ___________________ have done it without you!
  2. The repairs I made ___________________ have fixed the problem, but they didn’t – so I’ll have to take another look.
  3. It ___________________ have rained a lot last night – there are puddles everywhere.
  4. I ___________________ have watched that horror movie; it gave me nightmares.
  5. We ___________________ have known about this; nobody told us anything about it.
  6. If you’ve been trying to lose weight, then you really ___________________ have eaten all that ice cream.
  7. He ___________________ have finished a 500-page book in a single day!
  8. She never showed up. She ___________________ have forgotten about our appointment.
  9. He broke two of the plates while washing the dishes. He ___________________ have been more careful.
  10. They ate every bite of their dinner – they ___________________ have enjoyed the food.

Task 4. Complete each sentence B so that it has a similar meaning to sentence A. Use a modal verb and the correct form of the verb in brackets.

can’t – may – might not – must

1. A : I’m sure schools 50 years ago weren’t the same as they are nowadays (BE)
B : Schools 50 years ago ________________________ very different from nowadays.

2. A : It’s possible Josef went to school by bus . (TAKE)
B : Josef ___________________________ the bus to school.

3. A : I’m sure their holiday wasn’t very nice because the weather was so bad (HAVE).
B : With such terrible weather , they ___________________________ a very nice holiday.

4. A : I wonder if Jane remembers how to get here (FORGET).
B : Jane ____________________________ how to get here.

5. A : I’m sure Chloe isn’t still looking for her watch (FIND).
B : Chloe ______________________________ her watch by now.

6. A : We are going in the wrong direction (MISS).
B : Yes, we _______________________________ a turning.

7. A : Shakespeare and Voltaire weren’t alive at the same time, so they definitely never met (KNOW).
B : Shakespeare and Voltaire weren’t alive at the same time , so they
_________________________ each other .

8. A : Alison looks happy about her exam results, so she’s certainly done well (DO)
B : Alison looks happy about her exam results, so she _____________________________ well.

9. A : I’m not sure its right to blame Ray for that mistake (MAKE).
B : Ray ______________________________ that mistake.

10. A : Joe can’t open the door . Maybe he can’t remember where he put the key (LOSE)
B : Joe can’t open the door. He _____________________________ the key.

Task 5. Modal verbs for deduction. Choose the correct variant to complete the sentence.

1. You ______ finished that book already! You only started reading it an hour ago!

a. might have
b. shouldn’t have
c. can’t have

2. I think they ______ got lost – surely they’d be here by now!

a. can have
b. must have
c. should have

3. Oh no! My phone isn’t in my bag. I ______ left it on the train.

a. might have
b. should have
c. can have

4. She ______ been a lawyer but she decided to study accountancy instead.

a. might have
b. could have
c. may have

5. You ______ gone to Dan’s party – it was fantastic!

a. would have
b. must have
c. should have

6. I’m so sorry I woke you up. I ______ called you if I knew you were sleeping.

a. shouldn’t have
b. wouldn’t have
c. might not have

7. If you wanted to stay in that hotel you ______ booked before.

a. might have
b. could have
c. should have

8. He ______ committed the crime, as he had both the motive and the opportunity.

a. could have
b. can’t have
c. would have

9. If I had known about your accident, I ______ phoned you.

a. may have
b. should have
c. would have

10. Lucy ______ attended the concert, but we aren’t sure.

a. may have
b. can’t have
c. should have