Ответ:

1)TOM WAS SINGING HER A BEAUTIFUL SONG.

Past Continuous Passive

  • She was being sung a beautiful song (by Tom).
  • A beautiful song was being sung to her (by Tom).

2)SHE MADE HIM A CAKE.

Past Simple Passive

  • He was made a cake (by her).
  • A cake was made to him (by her).

3)THEY HAVE OFFERED ME A PROMOTION.

Present Perfect Passive

  • I have been offered a promotion (by them).
  • A promotion has been offered to me (by them).

То, что в скобочках, можно в принципе не писать. Это уточнение кем было сделано действие. Но вдруг надо будет — оно у вас уже есть)