【单选题】频率为 50 Hz ,传播速度为 300 m/s 的平面简谐波。波线上距离小于波长的两点,振动的相位差为 0.5π ,则此两点相距
【单选题】频率为50Hz,传播速度为300m/s的平面简谐波,波线上两点振动的位相差为π/3,则此两点相距( )。
【判断题】下定决心主要表现在两个方面:一是确定行动的目的,二是选择达到目的的行动方法和方式。
【单选题】其他条件一定时,一国货币供给增长将最终导致该国
【单选题】其他条件一定时,一国货币供给增长将最终导致该国
【单选题】下定决心主要表现在两个方面:一是确定行动的目的,二是()
【单选题】频率为 50 Hz,传播速度为300 m/s的平面简谐波。波线上距离小于波长的两点,振动的相位差为0.5π,则此两点相距
【单选题】听力原文:W: John, can you help me? I couldn't work out this math problem. M: I'm sorry. You can hardly expect me to do that. Q: What does the man mean? (18)
A.
He doesn't think he'll do that.
B.
He finds it difficult to do that.
C.
He has no time to do that.
D.
He knows nothing about math.