(67)处填()。
A.interval
B.region
C.range
D.compartment
A.
An og signal’s characteristic quantity representing data may (66) . at any instant, any value within a continuous (67) . For example, an og signal may follow continuously the values of another physical quantity representing data.
B.
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.