It is impossible that he is Spanish.
He can't be Spanish.
Did you hear me come in last night? No, I (be) -----asleep.
must have been
Perhaps he was at home yesterday.
He might have been at home.
I'm sure Jane is sleeping now.
Jane must be sleeping.
It is possible that you forgot your wallet at home.
You might have left your wallet at home.
I'm sure Jane isn't late today.
Jane can't be late today.
I had an umbrella when I came out but I haven't got it now.You (leave) ------------- it on the bus.
might have left
Perhaps he left the car unlocked.
He might have left the car unlocked.
I’m certain that she is a doctor.
She must be a doctor.
I'm sure she is at home today.
She must be at home today.