`4.` I was asked many difficult questions

S + was/ were + PP + (by O)

`5.` My piano is being repaired 

S + is/ am/ are + being + PP + (by O)

`7.` Children were looked after by her when we were out

S + was/ were + PP + (by O)

`8.` This room hasn't been used for ages

S + has/ have + (not) + been + PP + (by O)

`9.` The dog was hit in the garden by the boy yesterday 

S + was/ were + PP + (by O)

4. I was asked many difficult questions.

5.My piano is being repaired.

7.Our children were looked after by her when we were out. 

8. This room hasn't been used for ages. 

9. The dog was hit in the garden by the boy yesterday.  

$\text{-> Câu bị động thì Quá Khứ Đơn : S+was/were + Vpp + ( by O ) }$

$\text{-> Câu chủ động thì Hiện Tại Hoàn Thành : S + has/have + been +Vpp + ( by O ) }$