题型:选择题 如图所示为一列沿x轴正方向传播的简谐横波在某时刻的波形图.此时( )A.平衡位置在2cm到4cm范围内的质点速度方向沿x轴正方向B.平衡位置在2cm到4cm范围内的质点速度方向沿y轴正方向C.平衡位置在3cm到5cm范围内的质点加速度方向沿y轴正方向D.平衡位置在3cm到5cm范围内的质点加速度方向沿y轴负方向 查看答案
题型:选择题 25. ---You ought to have educated your son not to have eaten so much junk food, such as fried chicken, roasted mutton, smoked bacon and the like. ---I _______ . A.did but he didn’t listenB.ought to and he wouldn’t listen C.ought to have; but he didn’t listenD.should have but he hadn’t listened 查看答案