1. I finished my work at a about five o'clock
=> My work was finished at about five o'clock
2. we use this book in our class
=>This book is used in our class
3. They gave him a nice present when he retired.
=> He was given a nice present when he retired.
4. he opened the boxes and took out a cigarettes
=> The boxes were opened and a cigarettes were take out by he
5. do people speak english all over the world?
=> Is English spoken by people all over the World?
6. somebody planted this tree last month
=> This tree was planted last month
7. they built this house in 1995
=> This house was built in 1995
8. you must answer all the questions on the paper.
=> All the questions must be answered on the paper
9. someone is singing an english song.
=> English song is being sung by someone
10. we have learn english for five years.
=>English has been learnt for five years