A) 2 can't be 3 can't have been 5 can't be 7 must have dialed 8 can't have eaten Die anderen Nummern sind richtig :)
B) du sollst dir die Sätze laut vorlesen, um dann in C selber ähnliche Sätze zu bilden mit can't be, must be, can't have been und must have been.
C) zb He says, he doesn't want to go to the party. He can't be serious. Someone is coming. That must be them.
It was dark, so you can't have seen them. I'm sorry, that must have been my mistake. Bei A) 4 must have taken