如图所示，沿x轴正方向传播的一列横波在某时刻的波形图为一正弦曲线，其波速为200 m/s，则有

A．图中质点b的加速度在增大

B．从图示时刻开始，经0.01 s质点a通过的路程为40cm，此时相对平衡位置的位移为零

C．若此波遇到另一列波，并产生稳定的干涉现象，则另一列波的频率为50 Hz

D．若产生明显的衍射现象，该波所遇到障碍物的尺寸一般不小于200 m

"There is evil in every human heart, which may remain latent, perhaps, through the whole life; but circumstances may rouse it to activity.", which author of the following authors does the mention belong to

A. Washington Irving.


B. Ralph Waldo Emerson.
C. Nathaniel Hawthorne.


D. Walt Whitman.