認識五線譜

learning target:
1. Can deepen the understanding of the stave

The app is divided into two parts: study part and practice part

Study: Knowing the stave
- The app displays the staff under "Treble clef" and "Bass clef" respectively
- Then, instruct students to identify the additional line positions of the staff

Exercises
- Consolidate exercises on the above learning content
- All exercises are divided into three parts: "Treble Notes", "Bass Notes" and "Mixed Version".
- Each part of the exercise is subdivided into three kinds of ability exercises: one-star difficulty, two-star difficulty, and three-star difficulty