Question

voice change the mason is building the wall

Answer 1

The wall is being built by the masion.

Answer 2

ANSWER:

The newly formed sentence is 'The wall is being built by the mason.'

EXPLANATION:

When the subject is doing an action, it is an active voice and the subject comes before the action in the sentence.

Example: I clean well. (Where I is the subject and clean is the action)

When a sentence is written in passive voice, the subject is being acted on by the verb, so the subject comes after the action in the sentence.  

Example: Singing is something I do. (Where swimming is the action and I is the subject)