Bài 4:
`1.` A gift was sent to me by my old students.
=>My old students sent a gift to me.
`2.` You are not allow by the teacher to cheat in the exam.
=> The teacher doesn't allow you to cheat in the exam
`3.` My table is being fixed by my father.
=> My father is fixing my table
`4.` How long has this fax machine been used by Mr. Green?
=> How long has Mr. Green used this fax machine?
`5.` The singer was not recognized by his fan when he was at the restaurant.
=> The singer's fan didn't recognize him when he was at the restaurant
`6.` He will be disqualified from the competition by the judges if he uses drugs.
=> The judges will disqualify him from the competition if he uses drugs.
`7`. All the unnecessary lights will be turned off to save energy.
=> They will turn off all the unsuccessary lights to save energy
`8.` Jane was prevented from staying up too late by her mother.
=> Jane's mother prevented her from staying up to late
`9.` Was this document typed by Mr. Brown?
=> Did Mr. Brown type this document?
`10`. Many dead people were found by the recuers after the earthquake.
=> The recuers found many dead people after the earthquake
