He ____ ____ CCTV news every day.
Since our research so far has not produced any answers to this problem,we need to adopt a different________to doing it.
机械横波某时刻的波形图如图所示,波沿x轴正方向传播,波长λ=0.8m,质点p的坐标x=0.32m.从此时刻开始计时.