Question

write active into passive they have not done their work​

Answer 1

Answer:

this should help you

Explanation:

the work is still not completed by them

Answer 2

Answer:

Their work has not been done by them.

Explanation:

Following the rules or narration, one can easily do this. While converting active voice of perfect sentences into passive voice, we use "been" with has or have. Here, "has" is used because in the passive of given active sentence, work would be shifted to subject place and as it is uncountable singular, singular auxiliary "has" will be used.