1. They develop a friendly-to-the-environment type of washing powder.
⇒ A friendly-to-the-environment type of washing powder is developed.
2. Who said it?
⇒ It was said by whom?
3. The lady gave me the keys.
⇒ I was given the keys.
4. We must write to him.
⇒He must be written to.
5. John told Julia to up smoking
⇒ Julia was told to give up smoking by John.
6. They expected us to build the road.
⇒ We were expected to build the road.
7. Snow covered the mountains.
⇒ The mountains were covered with snow.
8. The professor is going to show the students an old bone.
⇒ The students are going to be shown an old bone.
9. His mom packed the bag.
⇒ The bad was packed by his mom.
10. Marie sells coffee.
⇒ Coffee is sold by Marie
CT : Chủ động : S + V +O ⇆ Bị động : S +be+ VPII + ( By O )