a) Example: We carry out many experiments in our laboratory.
Many experiments are carried out by us in our laboratory.
1. The secretary sent all the mail off an hour ago. 2. The doctor examined the patient and wrote out a prescription. 3. The students take written exams at the end of the term. 4. Columbus discovered America in 1492. 5. We often change our plans. 6. Shakespeare wrote 37 plays.
b) Example: He was given an interesting problem to solve. (the teacher)
The teacher gave him an interesting problem to solve.
1. The students were warmly thanked for the help (The Dean). 2. He was offered many books on the subject of his report. (a librarian) 3. The children were sent to the sea for summer. (the parents) 4. The questions were asked at the police station. (a police officer) 5. The experiment is discussed every day. (the scientist) 6. The delegates were interviewed near the hotel. (the newspaper reporters)