Tryng to use past modals

You should have been carefull ! I always say that to you that !
At midnight my sister wasn't at home, yet. Her flight must have been late.
You couldn't have got that job : you haven't worked hard enough !
I would have stayed with you but life worked against us.
If I met you earlier, our lives would have been different.

Tryng to use past modals

You should have been more carefull ! I always say that to you!
At midnight my sister wasn't at home, yet. Her flight must have been late/delayed.
You couldn't have got that job : you haven't worked hard enough! (to my English ears this one seems fine, so I'm not quite sure why the US commentors have highlighted the 'got' ...)
I would have stayed with you but life worked against us.
If I had met you earlier, our lives would have been different.

Ben fatto! 

Tryng to use past modals

You should have been careful! I always say that to you that!
At midnight my sister wasn't at home yet. Her flight must have been late.
You couldn't have got that job, you haven't worked hard enough!
I would have stayed with you but life worked against us.
If I met you earlier, our lives would have been different.