1.一平面简谐波的波动方程为 =-0.05sin [ pi (t-2x)] (m), 则此波动的频率、波速及各质-|||-点的振幅依次为 ()-|||-(A) dfrac (1)(2) ,1/2, -0.05 (B) dfrac (1)(2) ,dfrac (1)(2), 0.05 (C) dfrac (1)(2) ,1, -0.05 (D)2,2,0.05