Из действительного в страдательный. 1-the quests sang us a song. 2-i can recommend you a good book. 3-someone wrote me a funny letter. 4-tom is reading the text to me. 5-my boss has mentioned this idea to me.

1-The quests sang us a song. A song was sung by the quests
2-I can recommend you a good book A good book can be recommended me by him.
3-Someone wrote me a funny  letter. A funny letter was written me by someone
4-Tom is reading the text to me. The text is being read to me by tom
5-My boss has mentioned this idea to me. This idea has been mentioned to me by my boss