1,Those posters have just been painted 

2,A new bridge was being built by the builders 

3,A report is being prepared by Ba now 

4,Coffee was being made when I came 

5,The room has been changed 

6,Are your shoes being mended at the moment ?

7,The flowers haven't been bought yet 

8,He is being laughed at 

17,Mary was given this hat an hour ago 

18,I was told that our teacher was sick 

19,The telephone was invented by A.Bell 

20,That play was written by Shakespeare 

#good_luck 

$\text{⇒ Answer:}$

$\text{1. Those posters have just been painted (by they).}$

$\text{2. A new bridge was being built (by the builders).}$

$\text{3. A report was being prepared (by Ba) now.}$

$\text{4. The coffee was being made (by some one) when I came.}$

$\text{5. The room hasn't been changed.}$

$\text{6. Are your shoes being mended (by they) at the moment?}$

$\text{7. The flowers haven't been bought (by they) yet.}$

$\text{8. He is being laughed (by people) at.}$

$\text{17. Mary was given this hat (by someone) an hour ago.}$

$\text{18. I was told that our teacher was sick (by they).}$

$\text{19. The telephone was invited (by Alexander Bell).}$

$\text{20. That play was written (by Shakespeare).}$

                                    $\text{-----Done by Lhghbebong-----}$

$\text{Bài dài, yêu cầu lần sau chia khúc ra (╬▔皿▔)╯}$