题目

The flowers were so lovely that they __________ in no time.   A. sold             B. had been sold      C. were sold    D. would sell   答案：C一列横波在轴上传播，图甲为t=1．0s时的波动图象，图乙为介质中质点P的振动图象。下列说法正确的是（    ）     A．质点P在1．0s内路程为0．4cm     B．质点P在1，0s内沿轴负方向移动4m     C．波沿轴正方向传播，波速为4．0m／s     D．波沿轴负方向传播，波速为4．0m／s