Exercise 5: Change these sentences into passive voice
1. My father waters this flower every morning.
$\to$This flower is watered by my father every morning
2. John invited Fiona to brithday party last night.
$\to$ Fiona was invited to birthday party last night by John
3. Her mother is preparing the dinner in the kitchen.
$\to$ The dinner is being prepared by her mother in the kitchen.
4. We should clean our teeth twice a day.
$\to$ Our teeth should be cleaned twice a day
5. Our teachers have explained the English grammar.
$\to$The English grammar has been explained by our teachers
6. Some drunk drivers caused the accident in this city.
$\to$The accident was caused in this city by some drunk drivers
7. The manager didn't phone the secretary this morning.
$\to$The secretary wasn't phoned this morning by the manager 
8. Did Mary buy this beautiful dress?
$\to$Was this beautiful dress bought by Mary?
9. The German didt'n build this factory during the Second World War.
$\to$This factory wasn't built during the Second World War by the German
10. The Greens are going to paint this house and these cars for Christmas Day.
$\to$This house and these cars are going to be painted for Christmas Day by the Greens