声波的波长，声速和频率的关系为( )。
A．λ=C/f
B．λ=f/C
C．λ=fC
D．λ=C-f
参考答案：A
The science museum is near here. So we can go there _____________.[ ]
A. by bike
B. by bus
C. on foot
梯形螺纹牙型角误差或半角误差如何测量。
