Principle: Readings clearly show the successful voltage depending on the standard price of samples around a whole range of periods of the elemental frequencyLà lo?i hình x? s? ???c ch?n b?ng máy, ng??i ch?i có th? l?a ch?n m?t chu?i s? d? th??ng, g?m 3 b? s?:B??c two: M? ph?n “Ti?n ích” trong “Cài ??t Iphone” ho?c Ipad, tùy theo thi?