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问题 单项选择题 A型题

确定超声探头声能输出高低的主要因素是（）。

A.探头频率大小

B.电压峰强度

C.接收器的信号放大值

D.增益调节的大小

E.电流大小

答案

参考答案：B

解析：超声波的强度取决于输入电压的高低，改变输入电压即可改变超声探头声能输出的强度。

完形填空
完形填空。
       She is a(n)   1   girl.   2   name is Lingling.    3   is thirteen years now. She's    4   No.10
Middle school. She is in   5  . She has a good friend at school. He's name is Jim. He is   6   American
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(     )10. A. very               
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单项选择题

负责安全生产监督管理的部门实施监督管理，除了主动进入生产经营单位进行检查外，建立( )也是一种有效的监督方式。

A．舆论体系
B．安全生产责任制
C． * * 部门
D．举报制度
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