Translate into Chinese： （1)If the input to a linea...

Translate into Chinese： (1)If the input to a linear system is a sinusoidal wave, the output will also be a sinusoidal wave, and at exactly the same frequency as the input. (2)Just as we can express any signal as the sum of a series of shifted and scaled impulses, so too we can express any signal as the sum of a series of (shifted and scaled) sinusoids at different frequencies. (3)A signal is formally defined as a function of one or more variables that conveys information on the nature of a physical phenomenon. (4)Nyquist sampling theorem states that if the highest-frequency component of a CT signal x(t) is fmax, then x(t) can be recovered from its sampled sequence x(nT) if the sampling frequency fs is larger than 2fmax. (5) In fact, if a discrete-time sequence is absolutely summable, then its spectrum is, as in the continuous-time case, a bounded and continuous function of ω. (6) Systems are defined to be stable if every bounded input excites a bounded output. The condition for discrete-time systems to be stable is that all poles of H(x) lie inside the unit circle on the z-plane.