`43. ` Our teeth should be cleaned twice a day 

- Bị động với động từ khiếm khuyết should : S + should ( not ) be + V3 + ( by O ) 

` 44. ` The English grammar has already been explained by our teacher 

- Bị động thì HTHT : S + have / has + ( not ) + been + V3 + ( by O ) 

` 45 . ` Many accidents are caused in this city by bad drivers

- Bị động thì HTĐ : S + is / am / are + ( not ) + V3 + ( by O ) 

` 46 . ` His parents will be visited by Tom next month 

- Bị động thì TLĐ : S + will + ( not ) + be + V3 + ( by O ) 

` 47 . ` The secretary was phoned by the manager this morning 

- Bị động QKĐ : S + was / were + ( not ) + V-ing 

` 48 . ` This beautiful has been bought by Mary recently 

- Bị động thì HTHT : S + have / has + ( not ) + been + V3 + ( by O ) 

` 49 . ` Their house is going to be painted by the Greens before Christmas 

- Bị động TLG : S + is / am / are + ( not ) + going to be + V3 + ( by O ) 

` 50 . ` The cats have been fed by Ann twice today

`43`. Our teeth should be cleaned twice a day.

- Bị động của "should" ( + ) S + should be + Vpp + (by O)

- Chủ thể của hoạt động là ĐTNX nên không cần thêm by O.

`44`. The English grammar has already been explained by our teachers.

- Bị động thì hiện tại hoàn thành ( + ) S + have/has + been + Vpp + (by O)

(Câu 48 ; 50)

`45`. Many accidents in this city were caused by bad drivers.

- Bị động thì quá khứ đơn ( + ) S + was/ were + Vpp + (by O).

(Câu 47)

`46`. His parents will be visited by Tom next month.

- Bị động thì tương lai đơn ( + ) S + will be + Vpp + (by O)

`47`. The secretary was phoned by the manager this smorning.

`48`. This beautiful dress has been bought by Mary recently.

`49`. Their house is going to be painted before Christmas.

- Bị động thì tương lai gần ( + ) S + am/is/are + going to be + Vpp + (by O)

`50`. The cats have been fed by Ann twice today.