Đáp án:

`1,` A treasure had been found by him.

`2,` The game is won by her.

`3,` Video games are played by her everyday.

`4,` He was visited by them.

`5,` The housework is being done by him now.

`6,` Ice cream was being eaten by him.

`7,` School had been left by students early.

Giải thích:

Bị động:

- HTĐ $(+)$ S + is / am / are + V3 / PII ( by + O ).

- QKĐ $(+)$ S + was / were + V3 / PII ( by + O ).

- HTTD $(+)$ S + is / am / are + being + V3 / PII ( by + O ).

- QKTD $(+)$ S + was / were + being + V3 / PII ( by + O ).

- QKHT $(+)$ S + had + been + V3 / PII ( by + O ).

`1.` A treasure had been found (by him).

`-` Câu bị động thì QKHT: `( + )` S + had + been + VpII + (by + O) + time. 

`2.` The game is won (by her).

`-` Câu bị động thì HTD: `( + )` S + am/is/are + VpII + (by + O) + time.

`3.` Video games are played (by her) everyday. (Bị động thì HTD)

`4.` He was visited (by them).

`-` Câu bị động thì QKD: `( + )` S + was/were + VpII + (by + O)

`5.` The housework is being done (by him) now.

`-` Câu bị động thì HTTD: `( + )` S + am/is/are + being + VpII + (by + O) + time.

`6.` Ice cream was being eaten (by him).

`-` Câu bị động thì QKTD: `( + )` S + was/were + being + VpII + (by + O).

`7.` School had been left early by students. (Câu bị động thì QKHT)

`-` Chủ ngữ câu chủ động là các đại từ nhân xưng (I, you, we, they, he, she, it) `->` Chuyển thành câu bị động có thể không thêm (by + O)