1.Many trees were planted by us in our school garden.
2.Our classroom is cleaned by us twice a day.
3.The noise must be kept by us under 50 dbs here.
4.English is taught by them in our school.
5.A new bridge will be built by them over the river.
6.A new pencil-box was bought for me by them.
7.Trees are taken care of by people here.
8.Football shouldn't be played by us every day.
9.We are often helped by our teacher when we are in trouble.
10.Weren't you told about it by them?