Question

change active to passive who has done this

Answer 1

By whom has this been done?

Answer 2

Before beginning let us first know what are active and passive voices:

Active voice - A type sentence where in the subject of the sentence precede the object of the sentence.

Passive voice - A type of sentence wherein the object of the sentence precede the subject of the sentence.

Given sentence:

Who has done this?

Passive voice of the given sentence:

This has been done by whom? OR By whom has this been done?