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
