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)