A.
This song has been singing all over China for 50 long years. The melody still lingers in the air.
B.
This song has been sung all over China for 50 long years. The melody still lingers in the air.
C.
This song has been singing all over China for 50 long years, the voice of which cannot yet be forgotten.
D.
This song has been sung all over China for 50 long years, the voice of which cannot yet be forgotten.