急急急~~~英语被动语态与主动语态的转换

Question

（1）I bought the computer two years ago（改为被动语态）
（2）was the girl heard to sing an English song at the parly（改为主动语态）

Answer 1

1.The computer was bought 2 years ago(by me).
2.Did you hear the girl sing an English song at the parly?

Answer 2

the computer was bought by me 2 years ago

we heard the girl sing an English song at the parly

Answer 3

The computer was bought by me two years ago.
Did you hear the girl sing an english song at the party?

Answer 4

The computer was bought (by me) two years ago.
Everyone heard the girl sing an English song at the party.

Answer 5

The computer has been bought 2 years ago by me
Did you hear the girl sing an English song at the parly