患者腹胀痛，时有如条状物聚起在腹部，重按则胀痛更甚，便秘，纳呆，舌苔腻，脉弦滑，此证属（）

A.气滞血阻型积证

B.饮食积滞型腹痛

C.湿热壅滞型腹痛

D.肝气郁滞型聚证

E.食滞痰阻型聚证

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.

（69）处填（）。

A．duration

B．period

C．persistence

D．span