Complete the sentences using must or can't. ...
1 I'm certain they go to bed early on Sunday nights. They ...must go to bed early on Sunday nights
2 I'm sure John didn't stay late at the office. John ...can't have stayed late at the office.
3 I'm certain he hasn't arrived yet. He
4 I'm certain they are working together. They
5 I'm sure Amy hasn't finished her homework. Amy
6 I'm certain she was having a bath when I rang. She
7 I'm sure he hasn't won the prize. He
8 I'm sure she is looking for a new house. She
9 I'm certain Paul didn't invite Linda to the party. Paul
10 I'm certain you have been planning the project. You
11 I'm sure she was writing a letter: She
12 I'm certain they hadn't paid the bill. They
13 I'm sure he had been fixing the pipe. Hek

1. I'm certain they go to bed early on Sunday nights. They must go to bed early on Sunday nights.
- The word "must" is used to express a strong belief or certainty. In this case, I am certain that they go to bed early on Sunday nights based on my knowledge or past experience.

2. I'm sure John didn't stay late at the office. John can't have stayed late at the office.
- The phrase "can't have" is used to show that something is impossible or unlikely based on the available evidence. In this case, I am sure that John didn't stay late at the office because it is unlikely or impossible given the circumstances.

3. I'm certain he hasn't arrived yet. He can't have arrived yet.
- Again, the phrase "can't have" is used to express that something is impossible or unlikely. In this case, I am certain that he hasn't arrived yet because it is unlikely or impossible based on the information I have.

4. I'm certain they are working together. They must be working together.
- The word "must" is used to express a strong belief or certainty. In this case, I am certain that they are working together based on my knowledge or observations.

5. I'm sure Amy hasn't finished her homework. Amy can't have finished her homework.
- Similar to the previous examples, I am sure that Amy hasn't finished her homework based on the circumstances and available evidence. It is unlikely or impossible given the information I have.

6. I'm certain she was having a bath when I rang. She must have been having a bath when I rang.
- The phrase "must have" is used to express a strong belief or certainty about a past event. In this case, I am certain that she was having a bath when I rang based on my knowledge or observations.

7. I'm sure he hasn't won the prize. He can't have won the prize.
- Once again, I am sure that he hasn't won the prize based on the available evidence. It is unlikely or impossible given the circumstances.

8. I'm sure she is looking for a new house. She must be looking for a new house.
- The word "must" is used to express a strong belief or certainty. In this case, I am sure that she is looking for a new house based on my knowledge or observations.

9. I'm certain Paul didn't invite Linda to the party. Paul can't have invited Linda to the party.
- Based on the available evidence or information, I am certain that Paul didn't invite Linda to the party. It is unlikely or impossible given the circumstances.

10. I'm certain you have been planning the project. You must have been planning the project.
- The phrase "must have" is used to express a strong belief or certainty about a past event. In this case, I am certain that you have been planning the project based on my knowledge or observations.

11. I'm sure she was writing a letter. She must have been writing a letter.
- The phrase "must have" is used to express a strong belief or certainty about a past event. In this case, I am sure that she was writing a letter based on my knowledge or observations.

12. I'm certain they hadn't paid the bill. They can't have paid the bill.
- Based on the available evidence or information, I am certain that they haven't paid the bill. It is unlikely or impossible given the circumstances.

13. I'm sure he had been fixing the pipe. He must have been fixing the pipe.
- The phrase "must have" is used to express a strong belief or certainty about a past event. In this case, I am sure that he had been fixing the pipe based on my knowledge or observations.