题目内容：
声波的频率范围是（ ）。
A．20～200Hz B．20～2000Hz
C．20～20 000Hz
D．20～200 000Hz
参考答案：
答案解析：
单选题：声波的频率范围是（ ）。
- 题目分类：公共基础
- 题目类型：单选题
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B．20～2000Hz
C．20～20 000Hz
D．20～200 000Hz
B．20～2000Hz
C．20～20 000Hz
D．20～200 000Hz
一平面简谐横波的波动表达式为y=0.05Cos(20πt+47πχ)(SI)。取k=0，±l，±2，…，则t=0.5s时
一平面简谐横波的波动表达式为y=0.05Cos(20πt+47πχ)(SI)。取k=0，±l，±2，…，则t=0.5s时各波峰所在处的位置为（ ）。
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回答题:August 13th, 2008Dear Sirs,I am very happy to apply for
回答题:August 13th, 2008Dear Sirs,I am very happy to apply for the position of sec