Question

That portrait was painted by my grandmother change into passive voice

Answer 1

My grandmother painted this portrait

Answer 2

Hello mate,✌

Here is your answer:-

Dear,the question is already in passive voice.

Active:-My grandmother painted that portrait.

Passive:-That portrait was painted by my grandmother.

{Hint:To change active to passive, transform the sentence into past tense and use 'by' before the subject.The predicate comes at the starting while the subject comes after it.}

Hope that it helps you. ^_^