题型:名词解释 一简谐波沿x轴传播,t=0时刻的波形图如甲图所示,其中质点a的振动图象如乙图所示,则 ( )A.这列波沿x轴正方向传播B.这列波的波长为11mC.9s后x=9m 处的质点b的振动方向向上D.6s时间内质点o通过的路程为20cm 查看答案
题型:名词解释 She won’t lose weight______ she keeps a diet and takes exercise every day.A.unlessB.ifC.becauseD.since 查看答案