What elements does China traditional music lack?

There are four, seven or two notes missing. Supplement: Chinese classical music has five tones, namely: Gong, Shang, Jiao, Zheng and Yu (according to music theory, there are all tones between two adjacent tones); Therefore, they correspond to 1, 2, 3, 5 and 6 of modern music respectively, so they are two tones less than 4 and 7 (semitones between two whole tones).