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An instrument in E-flat major plays C major (there is no key signature in key signature) and records music in the major, and the phoneme (that is, Fu Tou) moves down two phonemes (for example, C major is in the third line and then moves from the third line to the second line). Why move down two phonemes? Because your saxophone plays C in E-flat, which is three degrees higher than C, do you want to play C? It is necessary to move down by a third degree. Move three times and twice. Play in G major (one sharp corner represents key signature), music score in E major (four sharp corners represent key signature), music score in D major (two key signature) and music score in B major (five sharp corners represent key signature). To put it bluntly, it is the addition and subtraction of the ascending and descending signs. The C major of E-flat saxophone is actually E-flat major, which contains three flat signs, so playing C major requires three sharp signs, and 3 flat +3 liters =0, which means that there is no key signature in C major. On the other hand, the saxophone in E-flat major is played in F major (one flat sign is key signature), so it is recorded in D major (second sharp sign), B-flat major (second sharp sign is key signature) and G major (No.65438 +0 sharp sign is key signature), while in E-flat major, it is recorded in C major (no sharp sign). I said a lot, looking at the trouble, if you think about it, it's actually very simple. Give you a picture.