问答题

从下列的句子中找到属于被动语态的句子，并讲句子的序号写在所给横线上。
 They punished the criminal. 
The work should be done at once. 
A watch was given to me.
They elected Tom monitor of the class. 
Bob onwed a house in the city.
Peter was helpt by John. 
属于被动语态的句子：