I'm sorry, I couldn't find the lyrics for the song "琵琶考级教材十级：天鹅" in the web search results. It seems that this song is not very popular or widely available online. Maybe you can try to contact the author or the publisher of the book for more information. Or you can listen to the song and try to write down the lyrics by yourself. I hope you can enjoy playing the pipa and learning new songs. ?