1.somebody has taken my briefcase.
=> My briefcase has been taken
2.The teacher returned our written work to us.
=>Our written work was returned to us by the teacher
3.The mad dog bite the little boy.
=>The little boy is bitten by the mad dog
4.The police have arested five suspects.
=>Five suspects have been arested by the police
5.The doctor ordered him to take a long rest.
=>He was ordered by the doctor to take a long rest