https://gist.github.com/TheaSang/8639a7fcea79287fd098b620849c456b
Firstly, I tried to directly add the random function into patcher and connected another two notes with this random function. But I found there were three notes playing together when running the program. Also, I was confused about how to achieve every two seconds change three notes.
After asking the professor, I realized that I need to create another component to control the player. Thus, these three notes can play separately and the problem of time also can be figured out.