Question

chage into passive voice the concert was finished at 12 p.m​

Answer 1

I guess it would be:-

By 12 p.m the concert was finished

Otherwise, I don't think that this sentence can be converted!Since there is no specific subject

Answer 2

Here's the Answer :

Question :

The concert was finished at 12p.m.( Already passive )

The Organisers finished the concert at 12 p.m. (active)

Explanation :

• In the process of change of active to passive the subject is changed to object and object turns to subject.

• When we turn we use suitable auxiliary to change the tense form of main verb .