Change the sentence into passive voice.
John Bradfield built Sydney Harbour Bridge in 1912.
Sydney Harbour Bridge built by John Bradfield in 1912.
Sydney Harbour Bridge was built by John Bradfield in 1912.
Sydney Harbour Bridge has built by John Bradfield in 1912.
Sydney Harbour Bridge has been built by John Bradfield in 1912.
Sydney Harbour Bridge had been built by John Bradfield in 1912.