`51.` The information had been received by the delegates before the recess.

`-` Bị động thì QKHT (+) S + had been + V3/Ved + ... + (by O)

`-` Trạng từ chỉ thời gian luôn đứng sau "by O"

`52.` His homework had been finished before she came.

`-` Tương tự câu `51.` 

`53.` The passage had been written.

`-`  Tương tự câu `51.` 

`54.` Trees had been planted.

`-` Tương tự câu `51.` 

`55.` I know that they had told him of the meeting.

`-`  Tương tự câu `51.` 

`56.` A fight had been started.

`-` Tương tự câu `51.` 

`57.` The window hadn't been closed.

`-` Bị động thì QKHT (-) S + hadn't been + V3/Ved + ... + (by O)

`58.` The paper hadn't been bought.

`-` Tương tự câu `57.`

`59.` Had the problem been bought by her?

`-` Bị động QKHT (?) Has + S + been + V3/Ved + ... + (by O) ? 

`60.` The paper will be received by John tomorrow.

`-` Bị động thì TLĐ (+) S + will be + V3/Ved + ... + (by O)

`@` Notes:

- Trạng từ chỉ thời gian luôn đứng sau "by O"

- Trạng từ chỉ nơi chốn luôn đứng trước "by O"

- Với các chủ ngữ chủ động là " I, he, she, we, they" thì khi chuyển sang câu bị động, có thể lược bỏ phần "by O"

- Với các chủ ngữ chủ động là " People, no one, some one,no body, ... " thì viết lại với câu bị động, phải lược bỏ phần "by O" 

Đáp án + Giải thích các bước giải:

`51.` The information had been received by the delegates before the recess 

`52.` His homework had been finished before she came

`53.` The passage had been written

`54.` Trees had been planted

`55.` I know that he had been told of the meeting

`56.` A fight had been started

`57.` The window hadn't been closed

`58.` The paper hadn't be bought 

`59.` Had the problem been solved?

`->` Bị động: Quá khứ hoàn thành:

`(+)` S + had been + PII (by....)

`(-)` S + hadn't been + PII (by....)

`(?)` Had +S + been + PII (by.....)?

`60.` The paper will be received by John tomorrow.

`->` Bị động - Tương lai đơn: `(+)` S + will be + PII (by....)