1. A lot of people use cell phones.
→ Cell phones are used by a lot of people 
2. Miss. Diep hasn’t taught us since the last semester.
→ We haven’t been taught by Miss Diep since the last semester 
3. Mr. Vinh teaches our English lessons.
→ Our English lessons  are taught by Mr. Vinh 
4. A student is doing that experiment.
→ That experiment is being done by a student 
5. Our teachers give us a free period this Saturday to prepare the festival.
→ We are given a free period by our teachers this Saturday to prepare the festival 
6. Did you buy this dictionary two weeks ago?
→ Was this dictionary bought two weeks ago? 

7. We should clean our teeth twice a day.
→ Our teeth should be cleaned twice a day 
8. Alan’s knowledge about science and technology doesn’t impress me.
→ I am not impressed by Alan’s knowledge about science and technology 
9. Her father drive all of us to school every day.
→ All of us are driven to school by her father every day 
10. They are going to build a new school here next year.
→ A new school is going to be built here next year 

1. Cell phones are used by a lot of people 

2.  We haven't been taught by miss Diep since the last semester 

3.  Our English lessons are taught by mr. Vinh

4.  That experiment is being done by a student

5.  We are given a free period by our teachers this Saturday to prepare this festival

6.  Was this dictionary bought two weeks ago?

7. Our teeth should be cleaned twice a day

8.  I am not impressed by Alan's knowledge about science and technology

9.  All of us are driven to school by her father every day

10.  A new school is going to be built here next year