1. The questions are diffucult, so we can't answer them.
-> If the questions weren't difficult, we could answer them.
2. They showed an interesting flim last night
-> An interesting was showed last night.
3. The actor interests us a lot
-> We are interested in the actor a lot.
4. The Vietnamese consider the New Year celebration a great holiday
-> The New Year celebration is considered a great holiday by the Vietnamese.
5. They made the girl run away
-> The girl was made run away.