1 The country was explored by them
2 The new factory will be built by them
3 The letters were posted yesterday by them
4 The truth will be told to him by them
5 It must be sent for him immediately
6 It just has been sent by them to him.
7 The crops can be picked by them by machines
8 Roads are constructed by people
9 Industry will need more new materials
10 More goods will be produced by people
11 The way was shown them by someone
12 He was taught English by someone
13 Money was given to me by someone
14 She was taken to hospital by someone
15 A cup of tea was offered to me by someone