在本辖区内出现首例流脑病例时，县级疾病预防控制机构应对病人所在地的医疗机构开展病例搜索，必要时开展社区病例主动搜索。
参考答案：对
用弯曲机弯钢筋时，应（）
A、划出安全区
B、设标志
C、禁止非操作工入内
D、有设计人员
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
