English modal verbs exercises

You can't have been sunbathing the whole week - you haven't got a suntan.
She can't have gone on holiday. She's got too much work to do.
She can't have eaten that whole bar of chocolate herself - it was very big!
Why don't you sit down? You must be exhausted after such a long journey.
He must have picked up this knife because his fingerprints are all over it.
It must have been Bob who left the lights on. He's always doing that.
Bob may have tried to call earlier, but I don't know for sure.
I'm not certain, but it might have been twenty to four.
Tom must have been mad to do something like that.
It was very foolish of him to ran after the robber. He could have been killed.