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【单选题】
关于超声波疗法的说法错误的是A.
常用的超声波疗法频率范围是800~3000KHZ
B.
交变电场的频率决定了超声波的频率
C.
超声波能在真空中传播
D.
超声波在同一介质中传播，发散角度很小
E.
超声波在介质中的传播速度与频率无关
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【多选题】建设工程项目环境管理的目的是( )。
A.
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B.
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C.
避免和预防各种不利因素对环境管理造成的影响
D.
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E.
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