1.The German didn’t build this factory during the Second World War.
→ This factory wasn’t built (by the Greens) during the Second World War.
2.The Greens are going to paint this house and these cars for Christmas Day.
→ This house and these cars are going to be painted for Christmas day by the Greens.
3. Ann had fed the cats before she went to the cinema.
→ The cats had been fed (by Ann) before she went to the cinema.
4.The students have discussed the pollution problems since last week.
→ The pollution problems have been discussed (by the students) since last week.
5.Have the thieves stolen the most valuable painting in the national museum?
→ Has the most valuable painting in the national museum been stolen (by the thieves) ?