Perhaps he left the car unlocked.
He might / could / may have left the car unlocked.
It is possible that you forgot your wallet at home.
You might/could/may have forgotten your wallet at home.
I'm sure Jane is sleeping now.
Jane must be sleeping now.
I'm sure she is at home today.
She must be at home today.
Did you hear me come in last night? No, I (be) -----asleep.
must have been
I'm sure you didn't ferget doing your homework.
You can't have forgotten doing your homework.
I had an umbrella when I came out but I haven't got it now. You (leave) ------------- it on the bus.
might / could / may have left
Kate is shivering. She ------------- be cold.
must
It is impossible that he is Spanish.
He can't be spanish.
John will probably come to the party.
He may / might come to the party.
Emily is crying. She --------------- be sad.
must
I'm sure they aren't at work today. )
They can't be at work today.
