1 can't have seen
2 ought to hand
3 was supposed to book
4 needn't have done
5 must have worked
6 should have told
Rewrting
1....might have known she would let you down
2...could have become a Canadian citizen if she had wanted to
3....don't have to state their age on the form
4....shouldn't have reactedso aggressively
5...had to turn back because of a rockfallon the path