1. David had gone home before we arrived.

⇒ After David had gone home, we arrived

2. They will hold the meeting before May Day.

⇒ The meeting will be held before May Day.

3. They will have to change the date of the meeting again.

⇒The date of the meeting will have to be changed again.

4. You mustn’t expect to be rich if you don’t work hard

⇒ Unless you work hard, you mustn’t expect to be rich

5. She was tired, but she stayed up late to watch the late film on TV

⇒ In spite of being tired, she stayed up late to watch the late film on TV

6. Scientists have invented new devices to help people live a longer life.

⇒New devices have been invented to help people live a longer life.

7. I don’t have enough time, so I can’t go on holiday this summer.

⇒ If I had enough time, I would go on holiday this summer.

8. A tornado destroyed hundreds of houses yesterday.

⇒Hundred of houses were destroyed by tornado yesterday.

9. Many rivers and lakes are poisoned. Factories produce waste and pour it into rivers and lakes.

⇒ Many rivers and lakes are poisoned because factories produce waste and pour it into rivers and lakes.

`1.`After David had gone home, we arrived.

`=>`Before `=`By the time `=`When + S + V2/ed, S + had + Vpp

`=`After + S + had + Vpp, S + V2/ed

`2.`The meeting will be held before May Day.

`=>`Bị động với tương lai đơn : S + will/ won't + be Vpp + (by O)

`3.`The date of the meeting will have to be changed again.

`-`Câu chủ động : S + will have to + V bare + O

`=>`Câu bị động : S + will have + to be Vpp + (by O)

`4.`Unless you work hard, you mustn’t expect to be rich.

`=>`Khi viết lại từ If về Unless, ta giữ nguyên một vế và trái vế còn lại ( vế chứa Unless không có "not" )

`5.`In spite of being tired, she stayed up late to watch the late film on TV.

`=>`S + V, but + S + V : ...nhưng...

$\neq$ Although + S + V, S + V : Mặc dù...

`=`Despite/ In spite of + N/Ving, S + V

`6.`New devices to help people live a longer life have been invented by scientists.

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

`7.`If I had enough time, I could go on holiday this summer.

`*`Cấu trúc câu điều kiện Loại 2 ( Unreal condition in the present ) :

If + S + V2/ed ( be `->`were/were not ), S + would/could/should (not) + V_inf

`=>`Câu điều kiện loại 2 là câu điều kiện không có thực ở hiện tại. Trong câu điều kiện Loại 2, vế đầu nói về một điều kiện mà người nói tin rằng không thể xảy ra trong hiện tại ( chứa If ), vế sau chỉ kết quả có thể xảy ra trong hiện tại.

`8.`Hundreds of houses were destroyed by a tornado yesterday.

`=>`Bị động với quá khứ đơn : S + was/were (not) + Vpp + (by O)

`9.`Many rivers and lakes are poisoned because factories produce waste and pour it into rivers and lakes.

`=>`S + V + because + S + V : ...bởi vì...