`1.` This building was built by them in 1970.

`=>` Câu bị động ở QKĐ

`=>` Cấu trúc: S + was/were + Vp.p + by O

`2.` A few letters are being collected by the postman

`3.` Some newspapers are being delivered by the postman 

`4.` A heavy bag is being carried by Mary

`5.` A picture has been already drawn by Mr. Brown

`=>` Câu bị động ở HTHT, cấu trúc: S + have/has + been + Vp.p + by O 

* Note

`->` 3 câu `2,3,4` được chia bị động ở HTTD

`=>` Cấu trúc: S + am/is/are + being + Vp.p + by O

1.They built this building in 1970 (chủ động)

⇒This building was built in 1970 (bị động)

2. The postman is collecting a few letters (chủ động)

⇒ a few letters were being collected by the postman  (bị động)

3.The postman is delivering some newspapers (chủ động)

⇒ Some newspapers were being delivered by The postman (bị động)

4. Mary is carrying a heavy bag (chủ động)

⇒ a heavy bag was being carryed by Mary (bị động)

5. Mr Brown has already drawn a picture (chủ động)

⇒ A picture has already been drawn by Mr Brown (bị động)