modals of deduction in the past

Choose the correct answer.

1. It can'twon'thave been easy being the only woman in the workforce.
2. Life mustcouldhave been hard for the first American settlers.
3. I suppose they canmighthave had help from the native people.
4. She mightwon'thave understood the local language. But I doubt it.
5. They can'twillhave travelled by boat. It would have been too dangerous.
6. He maywon'thave had help to build the canoe.
7. They maymusthave been exhausted working such long hours.
8. The family can'twon'thave gone outside much in the winter.