Passive voice : 1. They will finish their work next week 2. The fire has caused considerable damage 3. The police were following the suspects 4. We're going to give David a pig surprise 5. I think Alfred Nobel invented dynamite

`1.`Their work will be finished next week.

`=>`Bị động với tương lai đơn : S + will (not) + be Vpp + (by O)

`2.`Considerable damage has been caused by the fire.

`=>`Bị động với hiện tại hoàn thành : S + have/has (not) + been Vpp + (by O)

`3.`The suspects were being followed by the police.

`=>`Bị động với quá khứ tiếp diễn : S + was/were + being Vpp + (by O)

`4.`David is going to be given a big surprise by us.

or A big surprise is going to be given to David by us.

`=>`Bị động với be going to : S + be going to + be Vpp + (by O)

`-`Với câu bị động với 2 tân ngữ ( chia ở dạng be going to ) thì :

+) S ( người ) + be going to + be Vpp + O ( vật ) + (by O)

+) S ( vật ) + be going to + be Vpp + to/for O ( người ) + (by O)

`*`Note : Với chủ ngữ chỉ vật, chỉ dùng "for" khi Vpp là bought

`5.`Alfred Nobel is thought to have invented dynamite by me.

or It is thought that Alfred Nobel invented dynamite

`=>`Form : S + be thought + to have Vpp + (by O)

or It is thought that + S + V2/ed...