Ответ:
1) Portuguese is spoken in Brazil
2) A new road is planned near my house by the Government.
3) This house was built by my grandfather in 1943
4) Guernica had been painted by Picasso at that time.
5) The office was cleaned by the cleaner
6) Three books were written by him before 1867
7) You will be told later by John
8) The deal will be signed by this time tomorrow.
9) The work should be done by someone
10) Jimmy might have been delayed by the traffic
11) Mr. Brown is loved by everyone
12) A new stadium is being built near the station
13) The princess was eaten by the wolf
14) The story was told by someone at six o'clock
15) The milk was all drunk by somebody
16) The windows were cleaned by me before the storm
17) The computer will be repaired by the workman tomorrow
18) The passive will be studied in the next year by the students.
19) The dinner might be cooked by James
20) My wallet must have been taken by somebody