Answer:
1.A song is sang by him.
2.The spider was killed by the boy.
3.Let him be helped.
4.Maize is sown by the farmers in the rainy season.
5.Is a letter being written by you?
6.A canal was being dug by the workers.
7. The job will be finished by me by the end of this week.
8.Has the job been finished by you?
9.His mother's death has been informed by them.
10.All the necessary precautions were taken by them.
Explanation:
Hope these help:)