Why Three Colors? Puzzle of Quark's Statistics R-ratio in e+e- Annihilation I Neutral Pion's Electromagnetic Decay 1 Electro-Weak Anomaly Cancellation 日■■■■■■■■■■■■■■■■Why Three Colors ? Puzzle of Quark’s Statistics R-ratio in e+e- Annihilation Neutral Pion’s Electromagnetic Decay Electro-Weak Anomaly Cancellation ………………