The above example is a fact verified by writing code. As for the reasons, it will be analyzed in detail in this article. Here, it is only to illustrate that the above points need to be considered.夏正冲周围吼道：敌人只有一百。对于将来的天下形势都是不可估量的。Whether it is file uploading, music or video players, some obvious state distinctions can be found. For example, there are several states in the file upload program: scanning, uploading, pausing, uploading successfully and uploading failed. The music player can be divided into several states: loading, playing, pausing and playing after. When clicking the same button, the behavior in upload and pause states is different, and their style class is also different.Count of Cantmir尹旭轻轻舒了口气，说道：那就好，总算是可以舒缓一下筋骨了。14. Code: Scared to death.
