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问题 选择题

肺泡与外界的气体交换和人体内的气体交换依次是通过______实现的。[ ]

A．呼吸运动和扩散作用

B．呼吸运动和气体交换

C．扩散作用和呼吸运动

D．扩散作用和气体交换

答案

答案：A

单项选择题

安全检查是指对生产过程及安全管理中可能存在的事故隐患、危险和有害因素、安全缺陷等进行( )。

A．识别

B．监察

C．检查

D．查证
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单项选择题

An analog signal’s characteristic quantity representing data may (66) . at any instant, any value within a continuous (67) . For example, an analog signal may follow continuously the values of another physical quantity representing data.

A discrete signal is composed of (68) elements in time, each element having one or more characteristic quantities which can represent data. Examples of characteristic quantities are amplitude, waveform, (69) , and position in time. A digital signal is a special case of discrete signals, in which data are represented by a (70) number of well-defined discrete values that one of its characteristic quantities may take in time.

（70）处填（）。

A．limited

B．finite

C．restricted

D．bounded
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