1.She could have tried to carry this box away, but it was so heavy that she wasn't able to./ She could have tried to carry this box away,but it was so heavy that she could not manage to do it. 2.It is so hot in the car that you can boil eggs in it.
1) capital wants to have taken away this chest, but to have duplicated each other very much , she is unable to move at all. 2) this vehicle very hot , can be inside simply to have boiled eggs.