1. they cancelled all the flights because of fog.
All the flights were cancelled because of fog.
2. they have built this school for 2 years.
This school has been built for 2 years.
3. Phu Quang has composed a lot of songs about Ha Noi
A lot of songs about Ha Noi have been composed by Phu Quang.
4. Nam will buy a new bike next week. 
A new bike will be bought by Nam next week.
5. they clean their rooms regularly
Their rooms are cleaned regularly.