1) John wrote the letter. - The letter was written by John.
2) They spoke about it. - It was spoken about.
3) The doctor ordered him to take rest. - He was ordered to take a rest.
4) The teacher corrected our exercises at home. - Our exercises were corrected by the teacher at home.
5) Schoolchildren took out many books from the library. - Many books were taken by schoolchildren from the library.
6) The teacher will tell us an interesting story. - An interesting story will be told us by the teacher.
7) Fire destroyed the house. - The house was destroyed by fire.