What is the story of Yu Boya learning piano from his teacher?

During the Spring and Autumn Period and the Warring States Period, there was a pianist named Yu Boya who studied under Mr. Cheng Lian. He studied hard for three years and wrote a song called "Mountains and Rivers".

He is very happy to play music for the teacher. The teacher smiled and said, "I have a teacher who is much smarter than me." Tomorrow, I'll take you to see him. You are sure to gain something. "

Early the next morning, Cheng Lian and Yu Boya rowed to an island and told him, "The teacher is on the island. Find it yourself. After 10 days, I will pick you up again. "

After Mr. Cheng Lian left, Yu Boya could never find this talented pianist again. He sat breathless and fidgety at sea. In front of the endless sea, behind the towering peaks, Yu Boya cheered excitedly with the sound of "rushing" and the sound of beating pines. He suddenly understood the teacher's intention and immediately played the piano in the face of the sea.

10 days later, Cheng Lian really came. When Yu Boya played the revised music to him again, he repeatedly praised and said, "Good, good, great!"