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问题 单项选择题 A1/A2型题

超声波是怎样产生的（）

A.换能器的逆压电效应

B.换能器的正压电效应

C.换能器向人体发送电信号

D.换能器的热效应

E.换能器的机械效应

答案

参考答案：A

解析：超声波的产生是通过换能器的逆压电效应，接收回声信号是通过换能器的正压电效应。

单项选择题

张晓林是江阴市人民代表大会代表，由于其不能代表选民的利益，作风不正派，原选区选民50人依照法定程序要求罢免张晓林的代表资格。依照有关规定，罢免张晓林的市人民代表大会代表身份，须经原选区多少选民通过( )

A．过半数
B．2/3以上多数
C．全体
D．1/3以上多数
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单项选择题

A typical (160) language contains an applicative sub-language which approximates the mathematical abstractions of "timeless" functions applied to "spaceless" values, where the actual operation sequences and use of storage space during expression evaluation are organized behind the (161) . In this setting, values are data structures of low volume, typically a few computer words or less, which means that an illusion of spacelessness can be realized by having (162) results during expression evaluation stored at the discretion of the language implementation, and effecting parameter (163) and (164) operations through value copying.

A．transverse

B．transportation

C．transmission

D．translation
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