Underline the incorrect modal verb and replace it with a more suitable one. Sometimes more than one answer is possible.
1 They mustn't have seen Max-he's away on holiday.
2 Joe knew about the strike. He must have warned me!
3 I couldn't have yawned when Tim told that story. It was a bit rude of me.
4 It was so noisy. It's possible he ought not to have heard us.
5 l emailed Erin a week ago, so she can't have read it by now.
6 I don't know if Jake is coming. I left a note for him but he should not have seen it. ​