A.448Hz,432HzB.432Hz,448HzC.880Hz,220HzD.220Hz,880Hz
A.x=square(t)B.x=square(t,0.5)C.x=square(t,50)D.x=square(t,1)
A.幅值B.有效值C.頻率D.相位E.時(shí)延