ответ: учи английский!
Объяснение:
1) A sound of piano is heard in the hall by us.
2) This book was bought by me a week ago.
3) These letters have already been brought by the secretary.
4) They went home after the work had been finished by them.
5) This problem is being examed by our scientists now.
6) He was taught English by my mother.
7) Her brother was sent a telegram by me.
8) My sister is always taken care of by my friends.
9) He is always laughed at by his friends.
10) This house has never been lived in by us.
